Regenerative breaking on MMM

So, you'll notice none of the questions I ask are anything like anyone else's because, well, I'm a freak.

I am working on a diesel powered vehicle for a Biofuel race from Berkeley CA to Las Vegas NV. Basically, no matter what, we can start with 1 gallon of gasoline's worth of energy (battery charge, biodiesel, granola for the hippies on bikes.) All other energy needs to be collected AND processed during the trip from biomass. I want to try and make it on one gallon.

SO

I am working on the idea of a parallel hybrid system using an electric motor to get up to speed and a small diesel engine to generate electricity and power the vehicle at speeds fitting it's point of peak efficiency.

How would I generate power? Simply by applying a small amount of parasitic drag with the electric motor when the vehicle is running under diesel power until a desired battery level was reached (20% to 0% drag, depending on power levels.)

I'd probably be using 4ah leadacid for the battery source, which should accept a charge fairly readily.

How effective is the drag break at recollecting energy on the CC controllers, or is it simply a shunt that isn't useful for collecting power?

Thanks!

P.S. I just got my V3 in the mail this morning. That's for another robotic project, though.