back to article Toyota ponders plug-in hybrids

Japanese motor mammoth Toyota signalled a cautious move forward in the "green*" motoring revolution, announcing plans for studies into "plug-in" hybrid vehicles on Friday. Reuters reports that Toyota will supply a brace of modified Prius vehicles to the University of California, Berkeley, and UC Irvine, for use in the studies …


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  1. Peter Johnston

    Everyone forgotten TCO?

    Nice to see someone realising that electric and hydrogen power isn't power at all - just a way of moving power from power station to vehicle - and with usually 75% or greater losses along the way. Add in the fact that batteries are one of the most polluting things on the planet to make - and don't last that long (as anyone with a mobile phone will be aware). Batteries for a Prius cost upwards of £3k ($6k) and are guaranteed for 10 years - can you see people looking to buy an 8 year old Prius with that expense round the corner. When you consider that 80% of the environmental damage done in a car's life is done in making it, not using it - halving the life expectancy of a vehicle (av 16 years currently) is not a terribly green idea!

  2. Anonymous Coward


    is the answer... a permanent connected electric car running on power supplied by the road itself using crossovers to change lanes...

  3. TeeCee Gold badge

    Re: Scalextric.

    Where have you been? Scalextric cars have been able to swap lanes without crossovers for some time now. You can even run more than one in the same lane. Maybe the time *is* ripe to upscale the system to full size.

    Bagsy I get to be the bloke at the side of the road with the controller though.......

  4. Matthew

    @Anonymous Coward

    Would that be related to 'Scalextric'?

  5. Andy

    How is a Prius green, exactly?

    I mean, a lot of fuss is made over the fact that it's a hybrid and gets a better MPG -- although that is disputed.

    And I don't even mean the manufacturing costs. I thought that the idea of a hybird engine was that you could have a teeny-tiny engine to charge the battery and therefore use less fuel and produce less emissions. (This is called a Serial Hybrid, BTW.)

    The Prius has a 1.5l engine. Seems to me it would be greener to drive, for (UK) example, a 1.2l Corsa.

    Wake me up when someone actually produces a serial hybrid car.

  6. JeffyPooh Silver badge

    Emergency back-up power generator

    I live in a part of Canada (suburban Nova Scotia, just outside Halifax) that has more black-outs than many third world countries. The power goes out almost once per month, sometimes lasting for many hours.

    If someone were to offer a hybrid car than would also function as a backup 30kW emergency generator for my home, I'd seriously consider buying one.

    Such a capability shouldn't require anything more than a contactor, some sensors, a remote interconnect box, and some software.

  7. Anne van der Bom

    This is why the Prius is green


    I own a Prius, and with careful driving I manage about 4.7 l/ 100 km on average (summer & winter). This is better than a 1.2 l Corsa. Don't forget that the Prius offers more room and comfort than a Corsa. A Corsa-sized Prius would defnitely be more economical. Be careful with comparisons!

    You state that the Corsa would be more geen because it has a 1.2 l engine versus a 1.5 l in the Prius. The Prius has an Atkinson cycle engine, which has a higher efficiency, but lower specific power. It delivers 57 kW, less than the 59 kW the 1.2 l engine in the Corsa puts out. Do not assess the 'greenness' of a car by taking only engine displacement in consideration.

    A serial hybrid is not a good idea because the losses in the drivetrain are too high. The Prius tries to drive the wheels directly from the combustion engine as much as possible. In a serial hybrid all power from the engine would have to be converted from motion to electricity and back to motion to drive the wheels. I estimate that the real world efficiency of a serial hybrid drive train would be 80% at best, using current technology.

  8. Anonymous Coward
    Black Helicopters

    Hybrid is a scam

    I am so sick of listening to pop culture media fawning over hybrid technology.

    hybrid cars only use less fuel when they have less mass.

    The toyota highlander hybrid gets exactly the same gas milage as the toyota highlander with V6 gas engine.

    they do not alter laws of physics in terms of work produced per unit of energy.

    they make their own electricity under the hood at a cost of about $.67/KW (based on $3.00/gal US). I can buy electricity from the local nuke plant at $.05/KW. Plug-ins have the potential to save money for end users.

    But it's not green. Neither are the small flourescent bulbs (mecury).

    rant rant.

  9. Anne van der Bom

    Not quite so bad as you think

    @Peter Jonston

    You may be right about the 80% environmental damage being done in production. I know that producing a car costs about half as much energy as it will use during its life time. So production accounts for about 30% of total energy. But environmental damage is of course more than energy consumption. During its lifetime a Prius will save about 4000 l of gasoline (200.000 km * 2 l/100 km) over a normal car of equal size. Ask yourself this question: what is worse for the environment: producing a battery or burning 4000 l of gasoline?

    The low fuel consumption is not the only green aspect of the Prius, Toyota also took measures to make it more recyclable.

    You state: "can you see people looking to buy an 8 year old Prius with that expense round the corner". Your (wrong) assumption is: guarantee = lifetime. Think about that. How long is the guarantee on an average car, 2 years? By your logic that would mean that the life expectancy of an average car is 2 years! People buy second hand cars all the time, even if it is sold without any guarantee at all. I bet the Prius will be no exception.

    Battery life depends on how you use it. Deep discharges are most damaging to the life expectancy of a NiMh battery. That's why the Prius is programmed to avoid just that. And most consumer gagdets are not. Do not automatically conclude that because consumer gadgets often suffer failing batteries, the Prius will too.

  10. JeffyPooh Silver badge

    @Hybrid is a scam - and some suggestions...

    Minor nitpiks:

    1) Electricty is sold in Kwh (kilowatt-hours), not 'KW'.

    2) Compact flourescent bulbs might contain 1 to 5 mg of mercury. That's about the same as 35 cans of tuna (at the limit of 1 ppm). Note - you might actually eat the tuna (I wouldn't).

    Your complaint about the relative price of power is valid. That's why 'plug-in hybrids' might be the best idea yet.

    The thing I don't understand is why modern hybrids can't be All-Of-The-Above-Hybrids. Why does the mode choice have to be so hard-wired into the design? Couldn't someone design a hybrid that can be gasoline powered with electric assist (for efficient high performance), or electric powered with gasoline assist (to recharge on the road), and of course with plug-in recharge when available? It should be a simple software selection (automatic mode selection, perhaps with manual override). All it might require are some clever hollow shafts through the electric motor and perhaps an extra clutch.

    For example, my car happens to be supercharged, but that doesn't mean that it is always supercharged. If I lift my right foot from the floor, the computer turns off the magnetic clutch, the 'Kompressor' disengages to becomes an inert, mostly harmless, 20-kg lump of metal until the next time. Best of both worlds. See?

    The All-In-One-Hybrid could even be GPS-smart so that if you're almost home, it wouldn't bother recharging the battery using gasoline. It might even ask you, "Hey boss, are we planning to go out tonight?"

  11. Anne van der Bom

    It's a hype but not a lie

    Dear Anonymous Coward,

    According to the specs the Highlander consumes marginally less fuel on the highway, supporting your view. But in city traffic, consumption is significantly lower. Because city traffic is unavoidable in every-day car use, the Highlander hybrid will save fuel.

    You doubt whether the extra pollution (battery & electric systems) and/or cost is worth the gas saving. Good point, but it is another debate. You do not help your cause by distorting the facts.

    You call in the higher powers of 'the laws of physics' to prove your point, while you should be looking at the 'laws of gasoline engines', which dictate that efficiency varies depending on load en speed. Reminds me a bit of August Magnan who once used 'the laws of physics' to prove that bumblebees couldn't fly.

  12. Alan Jenney
    Thumb Up

    All it does is put the pollution back to the power station

    "All it does is put the pollution back to the power station" is quite a long-lived argument. When you look at the economic and environmental cost from the source to getting power to the road, there's a hell of a lot of mucking about.

    With petrol, you've got to pump the oil out of the ground, forward it to a refinery, refine it and distribute it in tankers (first in ships, then on the road) to filling stations. Then there's delivering the power to the road, with the efficiency of the internal combustion engine running at 15-20% at best.

    With electric, you've got to dig the coal out of the ground, transport it to the power station, where it is burned with around 85% efficiency. It's then distributed through the existing network (which isn't quite as bad as an earlier poster suggested) before charging the battery, where there are losses due to resistance. The power is delivered to the road with 85% efficiency. Trouble is, battery technology that is affordable, envinronmentally friendly and gives reasonable performance at the same time is only just starting to materialise.

    With hydrogen, the hydrogen has to be extracted from some other source (such as water or gas). This is very inefficient and in practice may use more energy than is actually contained in the final product. If you create the hydrogen away from the filling station or home, there are inherent problems in transporting and managing it. Or indeed, getting a wide enough distribution network going in the first place. And the current fuel cell technology uses rare and environmentally unfriendly products in its manufacture.

    Okay, with the electric option you could choose to buy from "green" sources, thus removing the reliance on fossil fuels and the inherent pollution but none of these is a particularly pretty or efficient way of doing things. The real answer is to eliminate the need for travel and transport...

  13. Alan Jenney

    How Green is a Prius?

    The trouble with a hybrid is that extra weight. A lot of the benefit is lost because you're carrying around a battery, a powerful electric motor and an extra bit of transmission to mix the power from each of the two sources.

    "All of the above" - well the Prius does do everything that you suggest (except the plug-in part): when accelerating uphill, both sources are used, when the gasoline engine is over-producing, it's used to recharge the battery. Adding the plug-in charger is only a technical issue: some conversions to achieve exactly this have been done for some time (in the US). You need a bit of kit to provide the suitable charge current converted from the mains and monitor the state and temperature of the battery.

    I'm not sure that the "mode" is hard wired into the design as suggested.

  14. Jan

    Regenerative braking

    I am surprised no one has mentioned regenerative braking on the hybrids so far. Prius uses regenerative braking to charge the batteries when you brake. This is energy that would otherwise be completely wasted as heat. For a 'laws of physics' argument, this alone would give hybrids an edge over regular gasoline cars, won't it ?

  15. Doug Korthof

    This article ignores the Toyota RAV4-EV all-electric plug-in car

    Toyota need not "study" plug-in cars, they need only look to the experience of hundreds of Toyota RAV4-EV drivers still loving their durable all-electric EVs.

    Why this article FAILS to mention the existing RAV4-EV, last sold in Nov., 2002, still running and still beloved by its owners, is a mystery.

    It's almost as if Toyota is ignoring its own car, and this article somnolently blathers on without mentioning that an all-electric plug-in car is ACTUAL, not theoretical!

    You an see pictures on and there are youtube videos:

    Secrets of the RAV4-EV:

    Yet this insipid article fails, like Toyota, to mention it??

  16. Anne van der Bom

    Almost but not quite

    Sorry for posting again, but there seems to be some knowledge lacking about the subject. This time it's the transmission of the Prius.

    "lot of the benefit is lost because you're carrying around a battery, a powerful electric motor and an extra bit of transmission to mix the power from each of the two sources"

    The mechanical transmission of the Prius is the example of simplicity. It's only a planetary gearset, with fixed connections to the engine crankshaft and electric motors and a chain drive to the wheels. There is no clutch, no gearbox. This planetary gearset is about the size of a soda can. This is actually an area where the Prius is simpler and lighter than a conventional car.

    According to my data, the total weight of the hybrid components is 171 kg. But you can not simply conclude that a non-hybrid Prius would be 171kg lighter. Without the hybrid components, the combustion engine would have to be heavier to compensate for the lack of power. A clutch and a gearbox would have to be added. The fuel tank would have to be larger, holding on average more kg's of gasoline. The brake disks would have to be larger due to the lack of electric braking, etc. etc.

  17. Name

    @All it does is put the pollution back to the power station

    For your information, assuming the coal mine is right next to the power station so no transport problems, the efficiency of a coal fired power station (Joules of electricity divided by Joules of heat from burned coal) is rarely more than 40%. One power station that I visited had a 39% efficiency, but when the electricity consumption of the coal crushers, cooling pumps etc was accounted for, efficiency was only 33%. This is related to the second law of thermodynamics - more useful work can be obtained from a certain number of Joules of heat if that heat is available at a higher temperature. The materials of the turbine blades and things like that limit the temperature that they can use and therefore the efficiency. That is why they need those big cooling towers, or a lake - there is a lot of low-grade heat to get rid of, the other 67%. In sensible countries, the cooling water is distributed to radiators in people's houses.

  18. Pyros

    They're missing something...

    Going small is good idea in general when it comes to fuel cells, electric, whatever, in reducing emissions/fuel costs... but I think they're missing their mark significantly.

    If you want to achive maximum results, aim for the gruniter machines--the trucks, SUVs, even rigs! If they produce a decent alternative, shrinking the basic model for a smaller car will achieve better returns in consumption/cost, due to aerodynamics/tonnage.

    Give it better thought, Toyota. You've got those massive trucks almost every Texan love to drive, why not make it cleaner? (And no, it's not an ulterior motive to save gas costs on my Nissan Titan King Cab SE...)

  19. Demian Phillips

    Cost of Prius Battery

    I got a quote from Toyota in the USA for replacement of a Prius battery (not the 12 volt one) and I was quoted three thousand dollars including install. Thats half of your US$6K.

    Given how off your facts and figures are, how can we relay on any of the data you provide?

    If you know anything about Mobile phones, you would know that they are not living in the same charge cycle/power management arena as the battery in the Prius. This means they do not wear out like you describe.

  20. Morely Dotes

    electric coal?

    "With electric, you've got to dig the coal out of the ground,"

    Funny, I don't remember seeign any coal at any of the hydroelectric plants I've visited. I didn't see any at the wind farms, either. No coal at the nuke plant I visited.

    Who burns valuable raw materials like coal to make electricity? Sounds distinctly Third-World. to me. Must be a Turkish idea.

    (Let the flames begin!)

  21. George

    Point sources for emissions

    Plug-in hybrids will improve the air quality in my area tremendously.The difference between having a million small power generators (car engines) and a dozen large generators (power plants) is that there's an efficiency of scale for pollution control technologies.

    Plus, even if we're talking about switching one fossil fuel for another (oil for coal) the United States HAS coal. Heck, the eastern seaboard is the Middle East of coal!

    Oh, and I pay a premium to get my power from wind generators. Even 14 cents a kWh beats the heck off of a gasoline bill of 35-40 cents a kWh.

  22. Steven Knox Silver badge


    They're not going small because they want to. They're going small because that's all they can do right now. If you look at the range of electric/hybrid vehicles out there, you'll see that the smaller and/or slower they are, the more efficient (and more likely to be all-electric) they are. Our technology simply does not store or convert electricity into motion efficiently enough for it to be effective with the big, heavy stuff.

  23. lglethal Silver badge

    @ All-in-one Hybrid

    The problem with an All-in-One Hybrid is that you require 2 engines, a fuel tank and a large set of batteries. Thats a hell of a lot of space taken up under your bonnet and a lot of weight and cost you have to carry around! Thats why the companies have to make a choice - either fuel hybrid or plug in...

  24. Anonymous Coward
    Anonymous Coward

    Thinking green...

    Plug in car needs more electricity (imagine the power bill after having your car - which needs lots - charging overnight).

    Some places already struggle to produce enough electricity.

    Some people can barely afford the power bill they currently have.

    The challenge then is to produce abundant electricity - so abundant that prices fall dramatically, allowing people to afford a completely electric vehicle - without harming the environment with the wrong type of power stations.

    It's kind of a catch-22 that needs the right technology in the right places. Punting greens cars is only great when they can be powered by green electricity.

    The best way to reduce electricity usage (thus making more available for cars) is to reduce the human population, which also reduces the number of cars on the road.

    No, I'm not suggesting we kill off the useless third of the population - just stop encouraging population growth. Seriously, we don't need more humans. We've got more than can be handled as it is. Stop breeding, dammit!

  25. Nexox Enigma

    Plug ins

    Nobody runs through the energy economics of this idea. By the time electricity has reached your plug, you've already lost 2/3 of the energy that was contained in whatever they burned to make that electricity. There are thermodynamic laws (namely the first and second) that limit a "burn stuff to make electricity" type of plant to about 40%. Add in the transmission losses and you realize that electricity can't possibly go higher than about 35% efficient.

    In the States that 'stuff' would be mostly coal, which produces more CO2 per unit energy than any other fossile fuel. Some of the coal plants in this country don't even have sulphur scrubbers yet, so they are still actively contributing to acid rain.

    The average small car engine is 40% efficient, and there is some room for improvement there, it just isn't financially beneficial to automakers yet. Diesels go even higher than 40%, but nobody wants to be caught dead driving one of those...

    So the plug in hybrid, assuming 100% efficient storage and release of electricity is limited to that same 35% that the rest of the electricity at the plug is, with zero room for improvement in the forseeable future.

    @Steven Knox:

    We can actually convert electricity into motion quite efficiently, we just can't store enough energy in batteries. The highest end lithium ion batteries can store about 1.8KWH/kg, while gasoline is more in the range of 12KHW/kg, so a factor of 6 or 7 higher.

  26. Gavin Nottage

    @ Anne van der Bom

    "I own a Prius, and with careful driving I manage about 4.7 l/ 100 km on average (summer & winter). This is better than a 1.2 l Corsa. Don't forget that the Prius offers more room and comfort than a Corsa. A Corsa-sized Prius would defnitely be more economical. Be careful with comparisons!"

    I'm running a diesel Megane estate with 1.5 dCi engine, achieving the same 4.7 l/100km (which is 60mpg). I have even more room than the Prius, and it's cheaper to buy and maintain. It wouldn't get me into London for free, but I don't go there anyway. If you look at smaller cars with good diesel engines then the economy is even better.

    To me, the world needs to use less fossil fuels. They're a finite resource, so will run out.

  27. Pyros

    @Steven Knox:

    "We can actually convert electricity into motion quite efficiently, we just can't store enough energy in batteries. The highest end lithium ion batteries can store about 1.8KWH/kg, while gasoline is more in the range of 12KHW/kg, so a factor of 6 or 7 higher."

    Continuing Nexox's statement, currently we can only pack so much battery onto a little car--geometrically it would be easier to load a larger vehicle with more batteries. Combine that with the braking technology that feeds back power, and you can get quite a bit just from the mass of the vehicle, I believe. (I don't know exactly how that technology works, but it does make sense that you need to apply more force over a longer distance just to stop a heavier car.)

  28. Dirk Vandenheuvel


    "I'm running a diesel Megane estate with 1.5 dCi engine, achieving the same 4.7 l/100km (which is 60mpg). "

    Diesel being the keyword here. Much more polluting that the Prius "normal" fuel.

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