I used to have a HPI rs4. Very nice car. Go nitro if many people have em near you. They're a bit harder to start, but alot more fun I think. Make sure you local hobby shop stocks parts for whatever car you want. Having to wait for parts sucks, and I garunatee you will break parts. I kept and *entire* extra kit in my parts box so I could replace anything while at the track (and besides its cheaper that way.)
Do yourself a favor, and by a fm radio if you go nitro though.