Every electric car I've ever driven handles regenerative braking in a different way. Some of them are good, some of them are very good, and some haven't quite worked it out just yet.
When I drove the Nissan LEAF mule last month, there was minimal regenerative braking from taking your foot off the accelerator, and the brake pedal activated the mechanical brakes. I'm told that the production LEAF will incorporate more regenerative braking, although nobody could tell me how that would be activated.
The G-Wiz activates regenerative braking through the brake pedal: the harder you press the brake pedal, the more regenerative braking you get. If you need lots of braking because you're stopping in a hurry, then the mechanical brakes get activated. Thanks to some really clever software on the later cars, most people won't feel the difference between regenerative braking and mechanical braking. When you are just driving along and take your foot of the pedal, there is a tiny amount of regenerative braking going on, but not a lot - the car happily coasts along quite nicely. The new REVA NXR is even better with regards to regenerative braking. Quite frankly, in this regard, REVA are the very best in the industry when it comes to incorporating regenerative braking. It really is very impressive indeed.
The Tesla Roadster handles regenerative braking in a very different way. You take your foot off the accelerator and the regenerative braking kicks in straight away. Leave your foot off the accelerator and the car will just come to a halt. If you use the brake pedal, that just activates the mechanical brakes. Basically, you don't need to use the brake pedal at all in most driving - just the accelerator. However, there is a fair amount of 'grab' in the regenerative braking system and it is up to the driver to feather the throttle to give a smooth drive. But then, you don't drive a Tesla for its smooth drive, right?
The Modec electric van incorporates regenerative braking when you take your foot of the accelerator, but its relatively minimal. There is no way to increase the regenerative braking and when you put your foot on the brake pedal, you're activating the mechanical brakes. The Aixam Mega City is similar.
The Mitsubishi i-MiEV has two modes for regenerative braking: relatively modest when you're in DRIVE or ECO mode, but significantly more in BOOST mode. I tend to drive the car in ECO mode for most of the time, shifting to BOOST when I want to slow down. The regenerative braking effect reduces as the speed reduces and shuts down at around 8mph and the car then just creeps forwards, which gives the car a similar feel to a gasoline automatic car. As soon as you press the brake pedal, the mechanical brakes kick in.
I had the chance to try the Mitsubishi i-MiEV with zero regenerative braking recently and I was impressed with how far the car would just roll. I personally think Mitsubishi should change the way regen works on their car to remove regen braking completely in ECO mode and max it out under BOOST so that it can completely stop the car.
With my G-Wiz, I hardly ever activate the mechanical brakes. In fact, I think I've probably only ever activated the mechanical brakes a dozen times in the past four years. With the i-MiEV, unless I have to come to a complete stop I rarely use the brakes. I drove about five miles this morning on a mixture of busy freeway, fast trunk road, and urban driving. Until I stopped outside my house I didn't use the brake pedal once.