Split driving line looped = Infinite Driving line!
Dunno how much attention the new split driving line feature has gotten so far on the other consoles, but I'm messing with it now on 360 and I've found the line CAN be looped back onto itself, making an infinite line! In the editor stream when it was looked at, Shogun tried to connect it to another spline point that was already split but he stopped there. Instead, connect it to a point after the split, which has only its main line and no others.
You can now go in circles until the timer runs out.
Checkpoints however, only activate once and hitting B after a second lap will return you to the first lap :/. Would need some Custom CP code to fix that.