I, (I mean, my son) built a winning car once. This was for our local fair, not the scouts, but there were well over a hundred cars. I learned: 1. Aerodynamics don't matter. His car was simply the block. I have woodworking tools- this was his choice. He painted Bengals colors on it - crudely. Not only was his car a block, the surface was rough. 2. Relieve the wood behind the wheels so that only a small part of the body near the axle contacts the wheels. 3. Rub graphite into all parts of the wheels and anything that contacts them. 4. Drill holes in underside of car and glue in lead. Distribute weight evenly. I used some cast pistol bullets. 5. Add slightly more weight than is allowed. Depending on the accuracy of the scale, you may be approved. If not, use a pocket knife to shave off a little lead and re-weigh until you have the max allowable weight. Good luck.