To some, putting one over on the corporate powers that be is as glorious a pastime as could be imagined, to others it's a felonious pursuit reserved for miscreants. Of course, even those in the second group would pause before defending car rental agencies. For everyone who feel they've been billed unfairly, gotten a piece of crap car they didn't ask for (or no car at all) or dealt with desk agents who don't represent the sunny dispositions of their TV counterparts, this tip is for you.
Cheat... Car Rental Companies [Maxim]
Bio-Friendly Car Rental [internal]