When my son made his I went to Mobil's Grease Lab and told them I wanted something slicker than Owl Sh*t and they gave me a few ounces of something they concocted- It had graphite, silicone, and who knows what, but it worked better than graphite alone. (the other kids wanted it)
After making the body 'aerodynamic' we painted it with some enron (sp?) paint used for aircraft because of wind drag, its a very hard coat paint that can be polished very finely- polished it until a fly couldn't land on it without sliding off!

Did the axel polishing and wheel dressing- The Lab also heat impregnated the axels with Dupont Teflon for me (I that and the secret grease was the trick)

The car won EVERY RACE IT WAS IN.