Electric cars & hybrids have regenerative braking. I.e. when decelerating, the electric motor is used as a generator to absorb kinetic energy from the moving vehicle, slowing it down & producing electricity which is used to charge the battery. Problem is that contaminants such as rust may accumulate on the surface of the under used mechanical brakes, reducing their efficiency. Under used brakes are likely to take longer to bed in, further reducing their effectiveness.
Check out the linked article for advice on how to fix these problems.
http://www.greencarreports.com/news/1073841_drive-an-electric-car-remember-to-exercise-your-cars-brakes / plugin plug-in plug in regen disk disc corrosion oxide oxidation rust scrape clean friction pad pads reduced efficiency stand on the brakes hard accelerate acceleration deceleration /
