Anyone have any Pinewood Derby tips/tricks?

My son and I are working on his Pinewood Derby car for Boy Scouts.

We do it together, and its fun, but this is his third year, and he always loses. Of course, you know how it is. Some of the dads are really competitive, and they take everything to the extreme just to win.

So anyways, I've decided to fight fire with fire, and I figure since I have some of the best and most devious minds (FABO) available to me (Muahaha), I'd like to find out if any of you know some tips or tricks to make our car faster.

For any of you that dont know about Pinewood Derby, they basically give you a rectangular block of pine wood, 4 nails, and 4 plastic wheels. You can shape the car however you want, but it must come in under a certain weight, and you can not use any bearings or anything like that. The only lubricant you can use is dry graphite.