I did in boy scouts, i won 1st place 4 times and best of show 5 times. We made my pinewood derby car into a few nascar cars and a craftsman truck, my dad and i. You have to really make sure the wheels are as straight as possible and there is nothing slowing the wheels. Second make it as aerodynamic as possible. Third your car will be going downhill, thus most of the weight should be near the front. Fourth, get it as light as possible per regulations including the weight you have to put in it.