We need to be thinking about the driver interface method for the technology. I have some thoughts on the subject to get this started. Please share, contribute and (constructively) critique your fellow contributors.
I suggest a simple wand that attaches to the shifter on the vehicle. Instead of interfacing to the existing pedal/brake system and worrying about all the details of the existing ICE (internal combustion engine) controls in various vehicles, we develop an entirely independent system and depend on the educated driver to use the controls appropriately. Push forward on the little wand to go forward, pull back to engage regenerative breaking, leave in spring loaded neutral position when operating as a conventional vehicle. If the vehicle has a standard transmission, the operator will be running in neutral and it will be natural to control from that point. For an auto tranny car conversion we are going to have problems with torque converter/transmission damage if the user drives without the engine idling - so dealing with that will complicate those conversions. I therefore suggest a simple early path to operation pursuing smaller standard transmission front wheel drive cars and a simple generic interface able to work on many car types.
Now ought we create and document what we think is an appropriate hardware set for the motor controller people to consider as they work through those technical details?