If so, how did you add them? Did you add it to the stationary point? Will this addition help with the distance of the car?
This is the goal:
"1. your car must be powered by no more than 2 rubber bands. may be any size. 2. body of car may be made out of most common household materials. wheels may be previously manufactured, but body can not be. 3. may not launch or catapult car. must be self propelled."