The SG Drifters use silvercan motors and PVC tires. It says so at the end of the 4th movie. As for the speed, it's most likely just how the action was videotaped.

And, oh yea. Cossie, not trying to knock you or anything, but how can Andrew say you're a pretty good drifter when he and the SG guys are from Singapore and you're from England? Just seems a little odd that you'd make a claim like that. Maybe it's cuz the RCU members aren't members of DRC Central and/or RC Dori?