- Design does nothing. This is the part your Cub can do, and it doesn't matter how it looks or what shape it is. It can just be a block for all it matters.
- Sand and polish the axles - start with course sand paper, and make your way to fine sand paper. This is also something your Cub can do.
- Buy an axle press from the Scout Store - this will remove any unstraight axles. It also has an end to arch the end of the nail so the flat of the nail isn't rubbing against the whole wheel. This reduces friction. I have 4 boys so this will be re-used by every one of them.
- Make sure your axles are straight. Any unstraightness will cause the car to veer right or left and cause more friction against the track.
- If your Pack's rules don't forbid it (ours didn't), raise one of the front wheels higher than the other wheels. This reduces more friction, because fewer wheels are touching the track.
- Weight! Weight! Weight! This is probably the most important factor. Go to the Scout Store and weigh your car (or use a package or food scale). It should be as close to the maximum weight as possible (usually 5 oz). Add more weight if needed. I bought some weights from the Scout Store, and added Pennies to increase the weight to the maximum. Fishing weights also work well for cheap.
- Put your weight in back. It shouldn't be too far, but right before and on top of the rear axle, and as much weight as possible back there will have the greatest effect. My son's car would some times be slower going down the track, but because his weight was in the rear, that potential energy converted to kinetic energy, and he would always speed ahead of the other cars on the straight-way. Be careful though - if the weight is too far in the back, the car will do a wheelie at the bottom, and lose speed (and some times jump the track!).
Lastly, look up others' stories! There are plenty of people on the internet sharing stories. Google, and Youtube are your friends!