Algodoo

A fine tuned transmission that may be useful to some.

If you want your vehicle to go twice as fast link the power source to the red circle and the tires with the pink circle. If you want it to go twice as slow do the opposite thing. It is fully mechanical and phunlet safe, make sure to change its density according to your vehicle's density. Also, please rate and comment.

I made a sample car in the scene, just delete the box and watch them go.