phy set vehicle wheel rotation ID, wheel, direction is normally used to get the wheels spinning correctly.
What format is the model you are using (.3ds maybe?) I always rig the models and then adjust the limbs using the example program to get it working right.
I would be willing to rig your model for you if you want and then export it in .x format for use with DP. You can email it to me if you would like. It will be tomorrow before I can do anything though. If you want to send your code I can see if I can get it to work.