A word of advise:
I learned the hard way that driving Zipzaps on the rug can be trouble.
These things are fuzz magnets. I've spent hours pulling hair, fuzz and other debris off the axles, motor shaft, and out of the gears.
Now I try to only drive them on my track. Which I mop before I use it. Yeah, I'd rather drive them, than spend hours pullin' out tiny pieces of fuzz with a pair of tweezers.