There also exist hybrid supercapacitors, which use a chemical reaction but act like capacitors. The best use of high-power capacitors is not as a replacement, its as a supplement. Current technology is not quite sufficient, but ideally it would mean that anything under a 20 minute drive could run off just the capacitor, which could(with sufficient infrastructure) charge in under a minute. It's not quite filling up on gas, but its closer.

I would like to see more investigation into turbine powered cars again, it may be more feasible now to build a car like we build trains (A prime mover generates energy for locomotive motors). I think the best way to transition from gasoline to electric would be to take advantage of existing infrastructure and make hot-swappable battery units. For medium drives you use batteries, which can be switched in a garage with a capacitor bank for short drives, or a unit with a small battery, a helicopter turbojet and a gas tank (Which, ideally, would run at a higher efficiency than an ICE).

The reason we haven't used turbines in the past as far as I know is mostly the start-up times and inability to idle. They don't really slow down, so sitting in stop and go traffic you engine is basically still on full blast. Ameliorate that with a battery and you're good to go, hopefully.