back to article Braking news: Tesla preps firmware fling to 'fix' Model 3's inability to stop in time

Tesla is to issue a firmware update before the weekend for its Model 3 to deal with a critical brake weakness that was highlighted by US website Consumer Reports. The publication found lots to like about the 'leccy saloon, particularly its record-setting range and insanely fast acceleration – but when it came to slowing down …

  1. Yet Another Anonymous coward Silver badge

    A different problem

    If car makers start competing on minimum stopping distance, and they all fit automatic braking radar - are we going to have a whole set of freeway pileups when half the cars in a stream of traffic can stop in 1/4 the distance of the others ?

    1. Lee D Silver badge

      Re: A different problem

      Only if people are twats and drive exactly on their minimal braking distance all the time.

      Braking distance is more seriously affected by how much G you can subject the user to than anything else. You can make the car stop on a sixpence, it'll just break your neck and make you unconscious in your burning vehicle.

      1. Anonymous Coward
        Anonymous Coward

        Re: A different problem

        Braking distance is more seriously affected by how much G you can subject the user to than anything else. You can make the car stop on a sixpence, it'll just break your neck and make you unconscious in your burning vehicle.

        Captain Pedant here. If you had said "stopping distance"*, that might have been mildly funny. Yes, the car will stop on a dime by crashing into a suitably substantial object, but that's not "braking", that's crashing. Braking distance remains limited by the traction of the tyres and the heat dissipation/sinking capability of the brakes.

        *"breaking distance" might also have worked.

        1. Anonymous Coward
          Anonymous Coward

          Re: A different problem

          > traction of the tyres and the heat dissipation/sinking capability of the brakes.

          If you were being Captain Pedant, then you should have at least made an effort to split out the "traction" element, for example:

          - Tread depth (the legal limit is the legal limit, its. not an indicator that braking distance will be as good)

          - Tyre makeup (there is a massive difference between cheap and expensive tyres)

          - Coefficient of friction (and whether you are in a μ or split-μ situation)

          - Tyre mismatch (hello tyre rotating wallies)

          Whilst μ is an important factor, tyres and your attitude to changing them has the most substantial effect. Most people are unfortunately tightwads in that area.

      2. Stoneshop Silver badge
        Facepalm

        Re: A different problem

        Only if people are twats and drive exactly on their minimal braking distance all the time.

        Ever seen any that don't?

        1. Steve Davies 3 Silver badge

          Re: Ever seen any that don't?

          Especially if you drive a Black Audi (taken over from BMW 3-Series).

        2. Screwed

          Re: A different problem

          Obviously you don't watch me driving.

          It does help to be driving in a part of the country where others also most often leave sensible distances. Of course there are idiots, but far fewer than where I used to live.

          Interestingly, both the distance that my car's adaptive cruise control uses and my own judgement are in quite close agreement.

          1. Anonymous Coward
            Anonymous Coward

            Re: A different problem

            > Interestingly, both the distance that my car's adaptive cruise control uses and my own judgement are in quite close agreement.

            Mine is usually set at two seconds, save in wet conditions or bad visibility when I go full scale (four or five seconds, don't remember).

        3. Anonymous Coward
          Anonymous Coward

          Re: A different problem

          > Ever seen any that don't?

          Yes, Central Europe + parts of Germany is quite OK, plus drivers tend to be polite. Capital cities excepted, for some reason rubbish drivers seems to be an inherent attribute of capitalhood.

      3. Ian Johnston Silver badge

        Re: A different problem

        Braking distance is more seriously affected by how much G you can subject the user to than anything else. You can make the car stop on a sixpence, it'll just break your neck and make you unconscious in your burning vehicle.

        The maximum deceleration to which you can safely subject a sitting human is around 9G - above that and internal organs start tearing off their mountings, which is a Bad Thing. For normal driving, you won't get tyres with a higher coefficient of friction than 1, so 1G is your maximum. Do what you like with brakes, ABS and regeneration - you're not going to hurt the driver.

        F1 cars manage about 5.5 deceleration at high speeds, by the way, but that's because (1) their slicks have a friction coefficient of around 1.5 and (b) aerodynamic downforce means they have several times their weight to play with.

        1. Lee D Silver badge

          Re: A different problem

          Well, that's some strange maths then.

          "The stopping distance of 152 feet from 60mph was “far worse” than any of the 500 “contemporary” cars the publication has previously put through their paces."

          152 feet = 46.3 m

          60 mph = 96.6 km/h

          https://www.johannes-strommer.com/diverses/pages-in-english/stopping-distance-acceleration-speed/

          from 96.6 to 0 km/g in 46.3m = -18.494 ~= 2G.

          And that's regarded as - I quote - FAR WORSE than any of the 500 contemporaries.

          1G is by far nowhere near your maximum just under braking.

          You can brake a pushbike and get 0.6-0.8 G under your own pedal power.

          And even then.... even 1 G of acceleration is like entering freefall FORWARDS. Falling from, say, two feet onto glass head-first. It's someone picking you up by your ankles and holding you 2 feet above a windscreen and then letting go.

          Even the Tesla does TWICE that and is being berated for poor braking.

          1. David Knell

            Re: A different problem

            Lee D - I'm not sure how you did your calculations, but you've made the classic mistake of believing the output of a calculator without filtering it through critical thought. Short of sticky tyres, fancier aerodynamics than a Tesla or running into something, the maximum achievable rate of change of velocity of a car is 1G.

            Putting your numbers into the calculator you chose gives a deceleration of 7.8 m/s^2, which is far more reasonable.

          2. dfsmith

            Re: A different problem

            I typed your numbers into the online calculator you cited, and it returned 0.8g deceleration. Since they're using the standard A=(V*V)/(2*D) equation, you might want to check your numbers. (Braking system strength tests intentionally do not test driver reaction time.)

            Under 1g of deceleration, it's like coming down a 1:1 gradient on a planet 40% denser than earth. (SpaceX has no plans to test it on a planet like that, AFAIK.)

            1. Voyna i Mor Silver badge

              Re: A different problem

              "I typed your numbers into the online calculator you cited, and it returned 0.8g deceleration"

              I think he confused km/h with m/s. 100km/h is only about 28m/s.

          3. T. F. M. Reader Silver badge

            Re: A different problem

            @Lee D - I am not entirely sure what exactly you input into the various fields of that online calculator.

            I just rely on my own understanding of kinematics for order of magnitude estimates. With constant deceleration the braking distance (i.e., without taking into account the driver's reaction time that can easily be 0.7s for an alert driver, adding ~18m at 96.6km/h to the stopping distance) is

            x = vt - at^2/2

            where v=96.6km/h is the initial velocity and a is the deceleration that we want to compute. The deceleration time is t=v/a, which yields

            a = v^2/(2x) = (96600m/3600s)^2/(2*46.3m) = 7.3 m/s^2 ~ 0.75g

            for the Tesla. It is not clear to me what exactly "far worse" means in the context, but presumably other cars get closer to 1g and the corresponding 35m (115ft) that other posters assert as the best in class.

          4. Stoneshop Silver badge
            Boffin

            Re: A different problem

            from 96.6 to 0 km/g in 46.3m = -18.494 ~= 2G.

            s(t) = s(0) + v0 * t + 0.5 * a * t^2 and v(t) = v0 + a * t. So with v0 = 26.8 m/s, v(t) = 0 and s(t) = 46.3m you get

            a * t = -26.8 m/s , 46.3 m = (a * t) * t - 0.5 * (a * t) * t , 46.3 m = 0.5 * 28.6 m/s * t

            t = 3.2 s, a = 26.8 / 3.2 = 8.2 m/s^2, slightly under 1G.

            And your dropping your head on to a glass plate as a comparison is neither here nor there, because that is a (gravitational) acceleration suddenly changing to an abrupt stop over very little distance, so there's at least a third order component at play. It's not at all comparable to tootling along at some speed, then stomping on the brakes.

            And in addition, attainable deceleration has nothing to do with initial speed nor with the motive power used for reaching that speed.

        2. Anonymous Coward
          Anonymous Coward

          Re: A different problem

          > The maximum deceleration to which you can safely subject a sitting human is around 9G

          You forgot to your time units. 50G for a few microseconds is quite OK (I can attest). 5G for two hours you will probably not be so healthy afterwards (5G sustained for a few seconds is my personal record doing aerobatics).

          1. Deckard_C

            Re: A different problem

            If remember correctly an america miltary guy (probably air force) did a lot of deceleration research by strapping himself on to a rocket sled and stopping it quickly. I think he got upto 50G before getting detached retinas, longer then a few microseconds but less than a second.

            I think you can sustain 9G for a few seconds in a Typhoon in a G suit which covers both you torso and legs with the proper training and practice.

            1. Anonymous Coward
              Anonymous Coward

              Re: A different problem

              "I think you can sustain 9G for a few seconds in a Typhoon in a G suit "

              That would be "positive G" i.e. being pushed into your seat by a "pull up" maneouvre. The safe value for "Negative G" (pushing the nose of the aircraft down) is lower, and can't be mitigated by a G suit in the same way.

              Either way, the "50 G" figure you're quoting will be from a sensor bolted to a sled, and although the seat attachment and straps holding the chap to the sled might seem stiff, they will have smoothed out the acceleration and he *won't* have experienced the full 50 G.

            2. Anonymous Coward
              Anonymous Coward

              Re: A different problem

              50G for 10 μs corresponds to a change in velocity of 0.018 km/h. Therefore, if he's resorting to a rocket sled, I would guess he's dealing with a time that is much longer than a few microseconds.

              I doubt it makes sense to talk about applying an acceleration to the human body for a few microseconds. The speed of sound in water is about 1500 m/s, so it'll take at least about 0.1 ms for a mechanical force to be transmitted through the body. If you apply a force for a shorter time than that then I would guess that you're dealing with an acoustic shockwave, whose physiological effects probably need to be assessed in a different way, and you'd have to either immerse the victim in water or use some kind of gel to transmit the acoustic shockwave into the victim's body. Experimental subject, I mean.

        3. Spacedinvader
          Stop

          1G

          Nissan GTR would like a word. Several in fact. It not only does more decelerating but also accelerating and cornering. "chief engineer Kazutoshi Mizuno’s team has recorded a maximum of 2.8 g in the corners and 1.9 g under full braking at the Nurburgring."

          Yes, might be on the "ring" but doesn't stop me doing 70mph and jumping on the (w)anchors to see what is possible.

      4. Anonymous Coward
        Anonymous Coward

        Re: A different problem

        "Braking distance is more seriously affected by how much G you can subject the user to than anything else"

        Just to show how fast you can stop (and accelerate a car) look at a proper sports car.

        "braked to zero from 100mph in a mind blowing 3.6 seconds"

        http://www.ultimasports.co.uk/Records/0-100-0

      5. Trigonoceps occipitalis

        Re: A different problem

        "drive exactly on their minimal braking distance all the time."

        I never drive exactly on my minimal braking distance, always much closer - I am Audi!

    2. Anonymous Coward
      Anonymous Coward

      Re: A different problem

      > are we going to have a whole set of freeway pileups when half the cars in a stream of traffic can stop in 1/4 the distance of the others ?

      No, because the braking assistance system purposefully stops you literally a couple of inches from the car in front. This is to a) leave as much stopping room as possible to the car behind you and b) make it *very* uncomfortable for the driver not to intervene before the car does.

      It is the human driver that is more the risk, as our tendency is to just slam hard on the brakes.

      Believe it or not, there are dozen / hundreds of engineers involved in every aspect of vehicle design, and if you thought about it, so have they.

    3. Chz

      The issue occasionally gets highlighted

      I do remember an American show test driving an E30 M3 many, many moons ago and concluding that it was outright dangerous on the road because it could stop in under 130 feet from 60mph. Though this would be back in the days when your average North American car was a 2 ton barge, and it quite probably *was* dangerous to use that sort of braking power on a highway.

      Though I still take issue with declaring it to be dangerous to have the *ability* to stop quickly when needed. The problem is drivers using that capability when they perhaps shouldn't. Motorcyclists die in hordes, but not usually via being rear-ended.

    4. Anonymous Coward
      Anonymous Coward

      Re: A different problem

      My car already has a radar for stopping but don't really want to test it so will have to take their word that it'll apply brakes (more than just me pressing the pedal) to avoid a crash.

      I, of course, am not an Audi/BMW driver so leave plenty of stopping distance (3 seconds) between the car in front.

      Sadly - Audi/BMW driver seems to always want to get in that gap ..

      I really want a Tesla - I test drove a Model X and it was great but expensive. The Model 3 will be great if they can get the kinks out of it and mass produce it.

  2. Chris Miller

    AFAIK, the 'stopping distances' chart in the UK 'Highway Code' hasn't changed since the first edition* - when a typical family saloon had drum brakes, operating on cross-ply tires a few inches wide.. There's no reason for the 'thinking distance' to change, but the braking distance really ought to be around half (or, more accurately, the assumed rate of deceleration should be doubled).

    * It certainly hasn't changed since I took my test nearly 50 years ago.

    1. John H Woods Silver badge

      Whilst I agree ...

      ... many people already drive far too close.

      1. Voland's right hand Silver badge

        Re: Whilst I agree ...

        .. many people already drive far too close.

        Come on, not everyone is driving an Audi or BMW.

    2. tip pc Bronze badge

      I remember watching that consumer show on BBC where they where moaning about fake brake pads (i only fit oem on my car and performance after market on my bike, i got fed up with squealing brakes from cheap third parties). The brand new fake pads did take longer than the genuine ones already fitted to the car but the fake pads stopped well within the Highway Code limit and not actually that much longer than the bedded in genuine pads iirc ~10% but thefake pads where strait out of the packet and even new pads out of the packet take a little longer especially if paired with new disks. i think it was this show

      https://www.bbc.co.uk/programmes/b06qz9y2

      the Highway Code stopping distances need to be updated to reflect modern cars, brakes, tyres, road surfaces etc. I bet even most brake & tyre MOT failures would stop within the limit.

    3. Yet Another Anonymous coward Silver badge

      But since nobody can estimate the distance to within a factor of 2x anyway....

    4. Mark 65 Silver badge

      Clarkson and chums demonstrated the misinformation that is the Highway Code stopping distances when they put a range of cards through a braking test from sports to cheap shitbox. All pulled up well within the distance.

      Problem as I see it is that common sense is in short supply on the roads. Many a time I've witnessed some tit in the outside lane racing the bollocks off of a Yaris and getting up the arse of something like an M3 or other car that would likely stop in half the distance it would.

      1. Anonymous Coward
        Anonymous Coward

        > some tit in the outside lane racing the bollocks off of a Yaris and getting up the arse of something like an M3 or other car that would likely stop in half the distance it would.

        Or, more importantly, a heavy vehicle or a bus. Except when fully laden (and even) stopping distance is far shorter than most cars. This is something that people who like to sneak behind fire engines¹ (in countries where people do that) would do well to keep in mind.

        ¹ Not to mention battle tanks. You definitely do not want to be too close behind one of those.

      2. wolfetone Silver badge

        "Many a time I've witnessed some tit in the outside lane racing the bollocks off of a Yaris and getting up the arse of something like an M3 or other car that would likely stop in half the distance it would."

        I was watching Car S.O.S the other week and Tim Shaw was trying to blag (like he usually does) performance brake pads for a car they were working on. The guy showed him several types of pads, and he gave them the highest performing pad that was road legal. Shaw asked why they couldn't have the higher performing pads and why they weren't legal. The guy said the higher performing pads are illegal because the car would stop too quick.

        In your scenario, the Yaris could have far better tyres and pads than the M3. More often than not (in Birmingham at least), the rude bois who drive the M3's throw on the cheapest tyres they can find and the cheapest parts they can afford, while spunking the rest of the money on removing the DPF and getting more power from the car.

        1. Grant Fromage

          Before the advent of all the brake pad compounds now available the split was fast road/rally and competition.

          Competition pads may fail an MOT because at the speed the test rollers run they don`t get warm enough to exert their full friction characteristics. There is min spec when cold for road legal.

          There was a classic mintex formulation (177?) and a non asbestos later version too that passed the MOT limits cold and were road legal.

          I found a motorsport garage through a mate from work cos i got fed up with being told that the pads needed changing soon. In the days before ABS with over servo`ed brakes they were a boon, If you found yourself in emergency stop you could stomp with at least half a second in hand to then cadence and lock and unlock as needed and they didn`t fade with disks glowing red down a 1 in 4 for a mile in first gear ( they exist) in Yorkshire.

          The biggest problem (IMHO) is driver awareness and reaction time. You need to put the fools on a simulator and see how many times they crash and maybe it will sink in. Maybe.

          My driving instructor was an ex RCT HGV instructor.

          It is very reducible:

          What can you see?

          Can you guarantee to stop in what you can see?

          If not F------well slow down.

          What happens if the vehicle in front has a seized engine or a transmission failure, suddenly, do you have an escape route round the carnage? Can you rely on your reactions to save you? Back off give yourself thinking and reacting time. Space=time= safety margin.

          I have a suspicion from the carnage word this was from being in convoys under fire and seeing the one in front go boom, but it is undeniably sensible

          I get seriously baseball bat wielding inclined with the self relievers who slot into my reacton space which would be fine at 30, not at 70ish, so I pull back to make time. Time after time after.........

          The most interesting thing was that some people teaching HGV now use the mantra gears for going, brakes for slowing, but in the days of only unassisted drum brakes you used what little airpump braking you get from the diseasel engine because a 5 mile descent isn`t a wise place to assume even disc brakes will stop all those tonnes or not fade like hell and have nothing at the bottom.

          The old wisdom is you select the lowest gear that will not over-rev the engine because pumping loss and therefore engine retardation in diesels is most at high revs

          I think the late Ian Dury summed up the " german car so rules don`t apply to me" syndrome with

          "premature ejaculation drivers" on new boots and.....

          1. wolfetone Silver badge

            "The biggest problem (IMHO) is driver awareness and reaction time. "

            I didn't really think of it like that until the day before yesterday. Driving home I turned right at a big round about that a 50mph dual carriageway goes through, with an exit to a smaller country lane. Turning right, one car stopped as one idiot in a Ford Fiesta ST sped past. No bother, it didn't affect me. His friend though, following/racing him in a Corsa didn't stop, nearly smashed in to me.

            I slammed the anchors on, he tried to. If I had relied on him to stop he'd have gone straight in to the side of the car. Thankfully, I know the roundabout and I anticipate dickheads like him speeding over. Throwing the car into 2nd gear while braking helps so much in reducing stopping distances.

            The wife was next to me, and she panicked (as she'd have took the full force of the impact if it happened - also I was driving my small Peugeot 107 so not a massive car). I joked with her saying it was a good job I changed the brake pads last week with Mintex pads, along with the brake fluid.

            Yesterday on the way home the wife said she had spoken to her friends about our near crash yesterday, and she believes if she was driving the car at the time she'd have smashed in to the prick and would've been badly hurt because of the speed he was going and the direction of our car. She wouldn't have used the engine to brake as she'd be worried she'd stall it. And she'd be right to think that, as it'd be easy done. But, like you say, it's the reactions. I didn't stall the car when I did an emergency stop, as I new I had high revs and could tell when the car was slowed down enough for me to engage the clutch.

            I've done nothing though to convince her she should drive me home after work during the week now though.

    5. Crucial Decimal

      braking distance really ought to be around half..

      While out riding my motorbike a few years ago, a tractor towing a large trailer pulled out in front of me blocking the road 100%. When I later calculated my stopping distance, I had approximately quartered the number given in the highway code. I was quite a bit above the limit initially - and hit the thing at ~10mph... Result was tractor 1, bike nil... I had a slightly broken leg.

  3. This is my handle
    Headmaster

    Small Typo

    Picking nits here but the publication is Consumer Reports -- it's plural. You got it right the 1st time.

  4. cd

    I don't want an algorithm between my foot and the brake calipers. He is Milo Minderbender the second, with tools.

    1. HamsterNet

      So

      So you don’t want algo between you and the breaks, so you drive a car pre ABS then? If not it’s already there.

      On any electric car there isn’t a servo, it’s all drive by wire. So the breaking response can be changed. Difference is only Tesla can do that on the fly. Everybody else requires a trip to a dealer, if you have received the notification.

      1. Anonymous Coward
        Anonymous Coward

        Re: So

        > So you don’t want algo between you and the breaks, so you drive a car pre ABS then?

        A Tesla-esque braking algo is *NOTHING* to do with ABS.

        Chalk cheese. Apples Oranges.

        ABS is a specific and simple concept based around tire slip.

        Tesla algo braking is some sort of blackbox "magic", that seemingly does not work that well.

        You can still threshold brake in an ABS equipped car, you probably can't in a "brake-by-wire" Tesla.

        1. NerryTutkins

          Re: So

          I assume the poor braking performance of the Tesla is related to energy recovery. In order to maximize the range, they're trying to recover as much energy as possible under braking by using the electric motors to charge the batteries, rather than apply the regular brakes and just burn off the energy as waste heat.

          But it would seem a bit clueless if they haven't programmed the braking system to be a little cleverer from the start - gentle braking using the recovery system (like F1 cars do when the driver lifts and coasts into a corner) but regular brakes with ABS and recovery if the pedal is hit hard. It shouldn't affect the range figures, as those I assume would generally be done while driving carefully, braking and accelerating gently, etc. rather than ragging it like you just stole it.

  5. Stoneshop Silver badge
    Headmaster

    "Tesla won’t stop until Model 3 has better braking"

    You don't say.

    1. David 132 Silver badge
      Coat

      Re: "Tesla won’t stop until Model 3 has better braking"

      Yeah, I just think a car with brakes is retarded.

      1. Lee D Silver badge

        Re: "Tesla won’t stop until Model 3 has better braking"

        Boom boom.

        1. Adam 1 Silver badge

          Re: "Tesla won’t stop until Model 3 has better braking"

          Shirley that's boom crash!

          Ah thanks, I was wondering where I'd left that coat.

  6. Blockchain commentard Silver badge
    Facepalm

    Well, that's stopping me fr5om getting one. Geddit !!!!!

    1. David 132 Silver badge

      I thought this thread would attract a better caliper of comment...

      1. Swarthy Silver badge
        Coat

        I think they were just padding their comment count, trying to drum up some votes.

  7. Charlie Clark Silver badge

    Hubris, meet unlimited liability

    Looks like this can be fixed with a firmware update

    As all car companies can tell Elon, that won't wash in a US class action suit. Whether it's this or something else, it's just a matter of time until the software industry finds the legal limits of providing software updates instead of product recalls and massive compensation and legal fees.

    I admire Musk but the financing of Tesla means he has absolutely no wriggle room for legal issues. But I suspect he'll still be able to sell the company at a profit to GM, Ford or Geely.

    1. Anonymous Coward
      Anonymous Coward

      Re: Hubris, meet unlimited liability

      I suspect he'll still be able to sell the company at a profit to GM, Ford or Geely.

      In a form I think you're on the money. I'd bet that Tesla Corporation will run out of cash, but before the insolvency bites there's then a claimed "merger of equals" (Bwahahhahahaaa!) with Ford or more likely GM. After which it turns out that Tesla shareholders did get an overly generous stake of the resultant combo, but the Tesla management are nowhere to be see. Meanwhile, Musk finds himself non-executive president, with his hands connected by a cable tie behind his chair, and some well-deserved gaffer tape over his gob.

      Five years later Tesla will be nothing more than a GM horse-stable brand, limping towards its retirement, like so many once-noble brands beforehand (Oldsmobile, Pontiac, Chevrolet, Saab, Hummer, and others).

      1. Alistair Silver badge
        Windows

        Re: Hubris, meet unlimited liability

        @Ledswinger

        Five years later Tesla will be nothing more than a GM horse-stable brand, limping towards its retirement, like so many once-noble brands beforehand (Oldsmobile, Pontiac, Chevrolet, Saab, Hummer, and others).

        eeeeeeeeeeewwwwwwwwwwwwww. Holy crap man, I though I was a raging cynical grumpy old bastard about the American Automobile manufacturers.

        About the only bit that can be tacked on that would be GM making Musk toddle off to congress, hat in hand begging for more bailout money.....

  8. DrXym Silver badge

    The way I look at it

    Even improving stopping distance by a single foot could mean the difference between your head going through the windscreen and not.

    It seems incredible that braking would be so terrible in a Tesla but perhaps the disc brakes are not up to the task of stopping a heavier EV. Maybe if they threw regen on in an emergency situation it would slow the car faster.

    1. Anonymous Coward
      Anonymous Coward

      Re: The way I look at it

      > could mean the difference between your head going through the windscreen and not.

      Not wishing to be unduly pedantic but ....

      If you are wearing a seatbelt in the prescribed manner, then the chances of your head going through the windscreen are less likely than $insert_your_choice_of_typically_unlikely_event.

      1. DrXym Silver badge

        Re: The way I look at it

        Tell that to the tree that you did or did not stop one foot in front of.

        1. Stoneshop Silver badge
          Boffin

          Re: The way I look at it

          Tell that to the tree that you did or did not stop one foot in front of.

          "Even improving stopping distance by a single foot"

          If your stopping distance would have been that one foot more, causing you to hit that tree instead of just not hitting it, then your impact velocity will have been quite low already. Let's say that you manage to decelerate at 6 m/s^2 for ease of calculation, then 30cm equals 0.5 * a * t^2 and t = sqrt(0.1) sec, so about 0.3 sec. Then with v(t) = v(0) + a * t. Final speed is zero, speed 30cm before that point is 1.8m/s, so about walking speed.

          You might bash your head against the windshield if you're Jeremy Clarkson sized and wedged in a Peel, with just centimeters to spare in front of your noggin.

          1. DrXym Silver badge

            Re: The way I look at it

            Tell that to the tree you were travelling into at 40mph instead of 30mph then.

            Frankly it's stupid reductive argument to claim that a shorter braking distance isn't a good thing, or that it can't mean the difference between serious injuries or not.

            1. Stoneshop Silver badge
              FAIL

              Re: The way I look at it

              Frankly it's stupid reductive argument to claim that a shorter braking distance isn't a good thing,

              Which is not what I'm arguing. It's just plugging the numbers and the situation you supplied into the applicable formulas, to show that a collision with a tree which you would have stopped one foot past had it not been there, would be only little more than a fender bender. And thus not very supportive of "stronger brakes == better".

  9. bassman314

    The Old Model 3?

    It doesn't look a thing like a waffle maker...

  10. JeffyPoooh Silver badge
    Pint

    Not according to Top Gear

    "According to the UK's Highway Code, the typical stopping distance locally is measured at 73 metres, 240 feet..."

    Jeremy told me that the 240 feet was the legal limit; the maximum acceptable stopping distance.

    Not "the typical".

  11. Henry Wertz 1 Gold badge

    "According to the UK's Highway Code, the typical stopping distance locally is measured at 73 metres, 240 feet or 18 car lengths."

    But who knows when that was updated? US legal minimum is 200 feet from 60MPH, but as far as I know this was set based on the technology available in the 1950s. I can tell you a 150+ foot 60-0 is very poor (after all, per the article a pickup truck can outbrake it!) These days, 90-100 foot 60-0 is an outstanding braking distance, a lot of cars (*cars*, not SUVs and trucks!) have braking distance 100-110 feet with even 120 feet being a bit long. I've had 3 or 4 cars without even 4-wheel disc brakes (rear drums!) and several of those mid-sized, that would still stop around 110 feet.

    "Braking distance is more seriously affected by how much G you can subject the user to than anything else."

    100% false. I've had plenty of cars that can stop the *wheels* from 60MPH in 1 foot -- that's called locking up the brakes. The tires have a grip limit that definitely limits your stopping distance. Also, the brakes do turn all that kinetic energy into heat, most cars that can stop from 60MPH in 110 feet or so, I think you'd find the rotors and pads would overheat and slip if you got tires on there that could stop from 60MPH in like 20 feet.

    I must say I find the performance of this Tesla alarming for 2 reasons -- 1) The whole concept of over the air updates, especially ones that will change important driving charcteristics of the car... I would find it quite alarming to start up my car one day only to find the brake responsiveness had been fiddled with overnight. 2) The dismissive attitude Tesla gave over this, "Ohh, ABS calibration." "Ohh, we got ours to stop in 130 feet" and "Ohh, well, that was an early model." Well, 130 feet is a poor stopping distance for something being sold as a high-performance vehicle. Standing on the brakes on dry pavement in a new vehicle should not give you 130 feet in one and 155 feet in a second copy of the same vehicle, don't try to pin that on motor trend, that's a problem. And ABS calibration should have been done by early production.

    1. Simon Barker

      "The dismissive attitude Tesla gave over this, "Ohh, ABS calibration." "Ohh, we got ours to stop in 130 feet" and "Ohh, well, that was an early model.""

      It's a bit late in the day to take what Musk says for granted but I'm sure he can milk the early production nonsense for a few more faults that pop up.

  12. Big Al 23

    Musk originally claimed there were no issues

    Earlier in the day yesterday Musk claimed there were no brake concerns on the model 3 even after CR showed unusually long stopping distances. You don't normally fix braking distance issues via software as the brakes are predominantly mechanical. Increased energy harvesting can shorten EV braking distances at the expense of vehicle stability especially on slippery surfaces. It remains to be seen if the software update resolves the issue and or creates new safety issues.

    1. vtcodger Silver badge

      Re: Musk originally claimed there were no issues

      "You don't normally fix braking distance issues via software as the brakes are predominantly mechanical ..."

      I was puzzled for a while as to how one juices up the disks or pads via software. But then it got through to me that Teslae use regenerative braking. So presumably they can send more power from the wheels to the batteries with only a software change. But that raises a bunch of questions like: Did they fail to test braking before shipping early production cars? If so, what else did they fail to test? Do they even have a formal test plan for the vehicle? Did they possibly initially set the braking distance high for a reason? What reason? What, exactly, is the tradeoff (if any)?

      I find all this less than reassuring.

      1. Big Al 23

        Re: Musk originally claimed there were no issues

        Standard braking is used with regenerative braking as a secondary option. You don't normally use regenerative braking to improve upon std. braking performance for street vehicles. Instead you use regenerative braking to recharge the battery in an EV. Tesla clearly has model 3 braking issues and a software update is likely to trade one problem for another.

        Tesla is suffering from huge technical issues, production issues, lawsuits, deaths from autopilot, lack of cash, alienation of investors, etc., etc. Now Musk has decided to stop everything and "reorganize" the entire production plant mid-stream, engineering and management. There is a lot of concern about Musk's sudden disruptive executive management decisions.

  13. jaffa99

    Heavily tested then

    This week, so this new braking firmware is going to get a couple of days testing at most. Hope it works better than the 'autopilot' concrete barrier detection.

    1. vtcodger Silver badge

      Re: Heavily tested then

      My understanding is that Tesla doesn't use LIDAR. That would presumably make determining the distance of a stationary object like -- Oh, I dunno, a crash barrier or a stopped firetruck for example -- much more difficult than one might think.

      That's an explanation, not a justification

      1. jaffa99

        Re: Heavily tested then

        In fact, since passenger cars are required to go through a type-approval process (and the Euro-NCAP in Europe) I'm surprised Tesla are allowed to develop, test (hopefully) and roll-out an update to the brakes (in just a few days).

        Surely an update that alters the performance of the braking system requires approval by the authorities that originally type approved the vehicles in different regions.

  14. Stevie Silver badge

    Bah!

    "ABS Calibration"?

    Shenanigans.

    The ABS should only kick in when a wheel locks up. There is no suggestion the car is leaving huge rubber skidmarks during the tests.

    What is happening is better described by the phrase "the brakes don't work adequately".

    I predict a recall.

    1. TRT Silver badge

      Re: Bah!

      Skidmarks may well be involved in testing a car with poor brakes.

    2. Adam 52 Silver badge

      Re: Bah!

      "The ABS should only kick in when a wheel locks up. There is no suggestion the car is leaving huge rubber skidmarks during the tests."

      If it is incorrectly calibrated and kicks in too early then you wouldn't get a locked wheel and you would get poor braking performance.

      Presumably the calibration is more complex that "wheel moving yes/no".

      1. Peter Ford

        Re: Bah!

        ABS systems usually detect the wheel slowing down abnormally, so they can release the brake before the wheel stops, so it is entirely possible that Tesla haven't quite nailed that.

        Still sounds a bit poor though...

        1. TRT Silver badge

          Re: Bah!

          It's far more likely to be a torque encoder than a rotation encoder.

  15. handle bars

    Does Tesla have to give a copy of every firmware version to a govt agency so that it can't change potentially dodgy software in a crashed car over the air before it is examined?

    If the car records a crash, and the firmware installed at the crash, and that firmware version is independently held for reference it would remove a clear potential issue in the future where the autonomous car or assisted function can not be "altered" post crash - and we know car companies have been dodgy in the past when accident / recall costs can cause them legal issues so we know they need to be stopped from being tempted.

  16. Evil Auditor Silver badge

    Is there also a firmware update which prevents its battery from catching fire? After a crash, that is. Anyhow, the guy who crashed and burnt last week in his Tesla is not going to complain but his family probably will.

    On an even more serious note: for petrol tanks there is rather strict regulation of what they have to endure without leaking. How is that for battery packs? A mobile phone battery fire is unpleasant, to say the least. But sitting on a whole bunch of such beasts, I'd rather they don't start burning.

  17. 0laf Silver badge

    I've never liked this trend to touch screens in cars. It means I have to look to carry out a function and can't do it by touch alone which I've been able to do on all cars since I started driving 24yr ago.

    Voice recognition is (in my humble experience) universally shite. I appreciate I sound like a Scottish farmer and I don't really expect these system to work for me, however my partner has a pristine cut glass English accent and they don't work for her either. So voice isn't really an alternative.

    There is a lot to be said for tactile knobs and switches I can find without looking. Despite their current woes VW does that the best of any cars I've been in (or did it was a 2007 car).

  18. James Cullingham

    Braking FUD

    Following the link to the page on that Driving Test website, we can see that it correctly gives the thinking & stopping distances from the Highway Code. At 30mph, this gives 30' (9m) thinking distance and 45' (14m) braking distance. Total is therefore 75' (23m).

    It also states: "Broadly speaking, stopping distances double when you’ve got wet conditions. On ice it’s worse: they’re ten times greater. So if, driving on a normal sunny day at 30mph, it takes you 23 metres to stop (that includes the time it takes you to see the hazard, process it, and react), then in icy conditions it could take you as much as 230 metres to stop."

    Seriously? My thinking time is also going to be multiplied by 10?

    No, my thinking distance will remain at 1 double-decker bus, not 10

    1. The Angry Badger

      Re: Braking FUD

      When you think about it, that claim doesn't really stand up to scrutiny anyway. 230 metres is a really long way.

      On level ground, you could probably shut the engine off and just let the car roll to a stop. Brakes not required.

      I suppose if you had a car going downhill, with bald tyres, no ABS and a driver with no clue how to drive on ice, then 230 metres might be possible. But for a halfway competent driver in an even vaguely maintained (ie road legal) car? Nah.

  19. cs9

    More importantly though...

    How's that "concrete barrier / not concrete barrier" firmware update coming along?

  20. Anonymous Coward
    Anonymous Coward

    Fuck me

    The level of ludditism here is astounding considering this is a tech site.

    We are at the early stages of a revamp of the car industry to electric and software controlled cars. There are bound to be teething troubles. Tesla are at the forefront - they may stay there, they may not, but to think they are going tits up is premature to say the least. Their production capacity problems are mostly sorted, they have investors throwing money at them, the cars are getting better every single day. What I don't understand is all the bad press. In the time that 10 Teslas have had accidents, there have been thousand from other manufacturers, and yet everyone is up in arms about Tesla. Beggars belief, can only be a smear campaign from competitors and oil companies who must be shitting bricks..

    With regards to brakes, the car still stops well within the highways codes requirements, and is going to get better without people having to drive off to a dealer and waste a couple of hours/days. Compare that to safety recalls for most other cars.

    It's a brave new world people - get used to it.

    1. Simon Barker
      Thumb Down

      Re: Fuck me

      If they can't get the basics right why do you believe they're going to get the more advanced aspects which haven't been nailed down yet right?

      If your brave new world requires us to settle for some of the worst performance in class then you can keep it thanks.

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