We need to build a car travel at least 5m on its own power. We're allow triggering devices ONLY if it's attached to the car. We cannot use any sort of motor which is electrical or commercial (nor living). We're not allowed to use Pinewood Derby Kits, dangerous chemicals (or CO2 cartirdges), any sort of track, or string. Those are the rules, so anything that doesn't explicitly go aginst them works. What I'm mainly looking for is the best propulsion system to keep the car moving at its fastest. Any suggestions? @ wtjui I like the idea but could you be a little more specific on what you mean by stabilizer fins?