Congratulations to warner54, 11, whose design got the most votes in our Top Builder: Balloon Car Challenge! Here's what they have to say about it:
First, I had the body of the car, a plastic water bottle. Then, I ducktaped the straw ( axles) to the bottom of the car. Then, I put the wood inside the axles. After that I put the wheels on by putting foam inside the bottle caps, and sticking them on. Then, I made a hole in the bottle, and I put the balloon on the car. My car went 2 ft. 11in. It went 5.4 in. per sec.