It's RPM btw. and radioshack is correct. They come with a 16,000 rpm motor. but it's not all that fast. Great for technical tracks like mine at home but if your just playing around on a table or kitchen floor it'll seem slow.
On a side note I need to get a digital cam and get some pics of my cars, track, and entry for the "worst" contest. mine is starting to look like a real life accident scene. . . lol Although I wish I wouldn't have tryed to lower my mustang.