Me and Kaleb (http://kalebtc.blogspot.co.nz/) did some balloon car science to figure out how far a balloon car can go with different attachments.
Here is our conclusion to this experiment. (A picture of the graph can be found on Kalebs blog as I am having technical difficulties with pasting it on my blog.)
The balloon car went the furtherest with no attachments, only a balloon with 2 puffs of air in it (time seconds: 3.7 distance meters 1.9.) With the paper parachute, it covered less distance but did it quicker, with an average of 2 seconds and 0.6m. The glad wrap parachute did worst. It averaged at 1.2m and 3.5 seconds. We figured out that the normal car goes furtherest because the parachute acts like a wind blocker and countered the exaust pipe (a straw) with a wind proof layer of plastic or paper.
By Joe and Kaleb