I am never having to fix my RC car, although I do need to get a new front drive belt. I have a RS4 Sport, but I have had it since they first came out and the drive belts were original. Last outing I stretched the front one badly and this particaular model did not come with a stock front belt tensioner. I'll be getting a new one in the next few days but other than that I haven't replaced anything on it, and its seen some heavy abuse for a street car.

Oh wait I did have to replace the 2spd gears once because the pinion came loose and chewed them up but otherwise even the gears take a beating without complaining.