Wii Racing/Flying section of the Amazon charts, anyway. Well, #2. So, really, the part about "the top of the charts" is misleading. It's on the top area of some charts. But it's Cruis'n. This is the only measure of success it'll ever see. Let Cruis'n have its day. How did Midway achieve this minor miracle? Simple! They dropped the price by 50% to $14.99. That's the only conceivable way to get this game sold at all. At that price, we're even kind of considering picking up a copy.
... And we just stopped considering it. But hey, if you need $15 worth of stuff to qualify for free ship'n, this is an option. Or you could wait for the price to drop some more. Oh, by the way, some other games are on sale too, including Trauma Center: New Blood and Donkey Kong Barrel Blast. But those aren't quite as hilarious. Paper Mario 2 for $10 isn't bad, though!
[UPDATE: Okay, Cruis'n is no longer on sale (why?) but all the other Wii stuff that you may actually care about for real is.]