A wind turbine in the car to make use of the breeze as you drive along?
Be ready for a new wave of people asking if you can have an alternator on the other wheels charging up the battery

I'm also interested in the solar panel bodywork that can charge the battery pack in 1.5 hours (don't worry, it'll be down to six minutes eventually!) and run a 212kw motor for an hour round a race track!!
article here