Road & Track recently reviewed an eBox by AC Propulsion, a Battery Electric Vehicle (BEV). BEVs and hybrids use an electric motor for acceleration and for some of the braking. The electric (regenerative) braking saves fuel, but it feels funny if you're used to old-fashioned brake pads and rotors, so the makers of the eBox put a little lever on the dashboard: how much regenerative braking do you want? At "min", you get a pads-and-rotors feel when you brake. At "max", lifting your foot off the accelerator pedal actually slows the car down a lot. You could do most of your driving without ever using the brake pedal.
We kind of take pedals for granted. In a traditional car, the right pedal is "go" because it controls the engine. The only way to "stop" is to use the left pedal. The eBox manufacturers did the same thing: the right pedal controls the electrics. I think that was a user-interface mistake. The electric motor/generator in a hybrid or a BEV is also used to slow the car down, and that's exactly what happens when you take your foot off the right pedal in an eBox: it slows down hard. People don't expect the right pedal to do that. That's why AC Propulsion had to put that lever on the dashboard. The most aggressive common current example, the Prius, has less than half the electric braking of the eBox.
Here's my idea for a BEV user interface. The right pedal should tell the motor/generator to accelerate the car. If the user takes their foot all the way off both pedals, the car could either coast (letting the wind slow it down) or hold its speed constant (like a cruise control). The driver should be able to select which behavior they prefer. Gently pressing the left pedal should tell the motor/generator to use regenerative braking to slow the car down, and pressing it hard should engage the mechanical brakes. This is all drive-by-wire and it shouldn't be too difficult to make the transition between the two braking modes seamless. Forget the lever.