At the first level (see 2011 Volta Grand Prix series info) we're using gasoline-powered karts at existing facilities, for the simple reasons that they're readily available, inexpensive and we need to train enough drivers.
Once there are enough capable drivers to race at the next level, Volta GP will introduce a pure racing kart chassis and electric power. It will be another level up in terms of handling and performance.
VGP will karts will be lighter, handle better, and be notably quicker. This is serious (and seriously fun) racing.
You're using electric power?
At the entry level we're still using gasoline-powered karts for cost reasons. When the next level is launched the karts will be electric.
There is a prototype running now which uses a DC motor capable of horsepower levels comparable to many gasoline-powered kart engines. Plus all the torque is available from zero RPM resulting in superb acceleration. This is the future of racing and cars in general. It's only a matter of time.
How fast does it go?
The prototype can quickly reach 50 mph and is gear limited, not power limited. Is this fast enough for you?
How long do the batteries last?
Lithium power will last long enough for a sprint race with no reduction in power. Since battery technology is constantly improving, this will not be an issue for any VGP kart races.
Is the throttle smooth?
Yes. Since the throttle is wired through a variable potentiometer, power delivery is extremely smooth - it drives exactly like your right foot tells it to.
The final specs are under development. But one thing is certain. Performance will be comparable to gasoline powered karts and it will continue to get faster as technology progresses.