Theres always this.No batteries involved and these are going the new Jaguar hybrid.1.6 litre turbo V6 rev at 18,000 rpm sounds perfect to me. I have gone away from the idea of KERS, not because of it's current limited power boost but because of the negative enviromental comments seen elsewhere. I read somewhere that the KERS batteries are used for one race before they are disgarded, this can't be good for the eco system.
http://www.williamshybridpower.com/