I find it convenient to have all the braking on the brake pedal.
If you want to slow down a little you know to ease of the accelerator a little. It becomes second nature. It really, really does. You don't have to be trained for that - my wife is definitely not trained, to put it mildly... and even she got it perfectly right after about 2 weeks - now she's better at it than in any previous car.
JeffC--Interesting essay. I appreciate that it made me seriously consider why I find heavy regen so appealing. I think there are two fundamental flaws in your analysis:
1) Regen does not upset the dynamic response of the car because it is done at relatively low deceleration rates (less than 0.3g). This has been discussed by others in the thread. I agree with your physical description of what could happen with trailing throttle oversteer, but traction control is fundamental to the safety of the vehicle. This is true if the driver lifts quickly and gets regen in a Tesla, lifts quickly at high revs in a manual transmission car, or lifts quickly in any car and impulses the friction brakes.
All of these situations are against the "first principles of vehicle dynamics" and all of them are managed my modern traction control. That's especially true with regen, because the regen is so low, vehicle upsets are within the ability of traction control to modulate. Empirical evidence supports this as people aren't suing Tesla for trailing throttle oversteer crashes in poor weather.
2) The statement that two pedals are needed (one for acceleration, one for deceleration) and other configurations are "incorrect in terms of basic human factor science" is unsupported. The only reason there are two pedals is because in olden times each pedal controlled an independent mechanical system.
In any car, we routinely accelerate using the left pedal and decelerate using the right pedal. Whenever we go up or down hills, the desired vehicle behavior can shift to the other pedal. Less braking is used to accelerate down a hill. Slowing down is done using less throttle up a hill. In addition, the vehicle always has deceleration forces therefore on flat ground it always decelerates with reduced throttle, independent of brake pedal use.
It's these always changing conditions that make it so much easier to have all the normally-desired deceleration commands coming from the same pedal as the acceleration commands. This is also why the classic two pedal system is flawed and why lifting throttle regen becomes second nature so easily. (BTW, I firmly believe that two pedals will always exist as long as humans are driving, because having that second pedal, for full force braking using a redundant system, is critical for emergency situations.)
So much driving is done with accelerations on either side of zero, between -0.2g and +0.2g, that it's odd to me that we have used two pedals for so long. Since you invoked human factors engineering, I'll submit (admittedly without evidence) that it is a fundamental flaw in vehicle design to have two pedals perform such similar functions that the driver must routinely decide which pedal to use depending on the specific driving conditions. With heavy regen commanded from the right pedal, the cognitive load is reduced as the right pedal is always used for typical acceleration and deceleration while the left pedal is only used critical stop situations such as emergencies or to keep the car from rolling.
Tesla was brave to implement the better solution knowing that it would be disruptive to driver habits, but they got it right.
