Are you talking about using an electric motor as a power assist? What powers the electric motor? If you power it off the trucks alternator you will have to burn more fuel, just like running ac. You can't make electricity without an energy source. If you cover the truck in solar panels and charge batteries with them just for the golf cart motor you may be on to something. How would you regulate the power it required so that it actually assisted the motor instead of loading it down. Like geezer101 says though, loading the crank from the balancer might not be wise.