Surely it cant be to hard if you can track an object over time (obviously more than 3 data points required, the more the better). You can do simply speed and curve projection (like i said in basic form 3 would work, drop the oldest on next read and re project). This also gives you the speed and projected speed.
Driving patterns can be fairly easy with maths to replicate, you just have a routine that works on distance and the greater the distance available for breaking feeds into the rate of breaking. In emergency situations where an extended breaking period was deemed safely possible (read in other input and calculate based on distance to target). Graceful breaking isn't that hard.
What hard like someone else said is to the write in all the finer subroutines that govern projections based over time based upon target being tracked, ie if target has previous increased rate previously to that of expected target it would simply read in the targets previous offset level and average it back across time (previous points) to give an expected result.
The more you open a can of worms on reading in the finer subroutines that allow you to fine tune projects on other targets the more things you discover you have to compensate for i guess.
But this is realistically only a part of what the smarts are about, its about doing what drivers take for granted and do automatically (well most of us), humans take all the complicated sensory from the car, feeling traction, weigh distribution and putting that to our advantage to go faster and/or go safer, some to a varying degree sadly.
Its really a golden time as things like cruise control, 4 wheel stability and breaking control has come a long way from the more crude systems of the past, making things possible.
Cars that are not only smart enough to drive you to the shops and avoid all the other idiots on the way, but could also put in a good time round a track in your name if you wanted, without sliding you into a tree at the first attempt at 50 on wet corner because its not programmed to react or compensate or expect for reduced friction on the road surface.
Everyone is scared of the day the privilege of driving will start slipping away and will be taken from us the moment its generally considered safer than manual control.
So what's going to happen when those of us out there with the know how start to back engineer the safety limits (raising the bar maybe, rate of acceleration, breaking, etc, etc) in the system and to also add in our own subroutines :) everyone loves to tweak right, every one wants theirs to be that special one, the ones that's just that bit faster than the rest.
You can take the petrol head out of the drives seat, but you cant take them out of the car... :-p