We only average 9kw around the track. This is not a fast car. We will use 30kw when accelerating though. Theoretically we should be able to run a 10kw portable generator powered by a 1 or 2 cylinder lawn mower engine and use the super caps as an energy sink to store power while we are decelerating to power our next acceleration. That's how it all works in our heads.
If I take a portable generator out of its frame and remove all of the extra stuff from it, then I should be able to bolt it down in the back hatch area.
A bank of caps that will give me 30 seconds of full power will take up 2 cubic feet of space. That should fit in the car as well.
I don't know about the danger. One explodes and is over with. The other creates a super-hot fire than can't be put out until it burns itself out. Either is probably less dangerous than a tank full of gallons of a highly flammable liquid.
Everybody grab your brooms, it's shenanigans!