They have "pre-cut" pinewood derby cars in a number of patterns. At least in Frisco, TX (suburb of Dallas here) they do.
You still have to do the "fine" carving, but the basic pattern is taken care of.
More tips:
1. There are pinewood derby "wheel alignment" kits. If you want to win, your car needs to go straight. If you can't find one of these, just make sure the axles are square to the car.
2. Graphite is useful on the nails as a lubricant.
3. Weights help redistribute the mass of the car.
It depends on how nuts you want to go with this. I'm the run of the mill racer, but my son's best friend (or his dad) goes nuts with this.
And they won first place this year.
Glen