How many Priuses can you fit in your wheel wells before you have to take a stick and poke them loose?
I can't speak for a Hummer but with my Dodge Ram truck (with the 5.7 Hemi and 20 inch wheels of course) I gotta clean the wheel wells out when it gets up to 14 or so Priuses.
My wife, the wimp, hasta start cleaning them out of her Durango at 5 or so.