Dear Friends
You may have spotted this item
http://uk.cars.yahoo.com/10032011/36/screwdriver-powered-car-0.htmlThe trike powered by two battery operated screw drivers. A good design exercise but rather killing on the old knees and the back as there is no proper saddle, and the complicated hinge in the middle looks rather heavy compared with the rest of the light weight machine.
Still you are unlikly to travel far on two batterys, unless you have a big pocket full of batterys to replace as you drive along.
I hope he does not give up the day job.
Chris Thomas