Re: Cars
It's becoming almost necessary for hypercars as hybrid tech is also on the new Porsche and LaFerrari.
Extra couple hundred HP/torque to the wheels on demand. The torque curve for electric is maximum at the low end, so they give an instant torque boost off the line. Can be recharged with excess engine power or a KERS (brake energy system) like in F1. Allows push to pass like in F1.
Only drawback is they're on the heavy side and can mess with weight balance, but the technology's rapidly improving.
It's becoming almost necessary for hypercars as hybrid tech is also on the new Porsche and LaFerrari.