What does a hydrogen-powered car sound like? Like this. The Riversimple Rasa:

Audio clip of the Riversimple Rasa accelerating. The Rasa has four electric motors, one in each wheel; brakes recover over 50% of kinetic energy when braking. Super-capacitors to store this energy and provide most of the power for acceleration. The cruising speed is provided by a hydrogen fuel cell ( 8.5 kW).