What parent said is correct, categorically or not: regenerative braking does not use conventional pad-and-disk. It uses the electric motor to slow the car by turning the motor into a generator. The fact that a Nissan Leaf has pads and disks does not change this.

This really isn't that complicated. Electric cars use a combination of regenerative braking (using the generator to convert kinetic energy; forward velocity, into electric energy) and using the disc brakes when regenerative braking doesn't slow you down fast enough. This results in much less wear on the brake pads and callipers.

Take a look at this: http://en.wikipedia.org/wiki/Regenerative_brake

Yes, the leaf has standard brakes... but it also uses regenerative braking to recapture some of the car's forward momentum without using the brakes.