Tipping for car rental upgrade in Las Vegas

[just my lucky day]

Has anyone tried to upgrade their car with the $20.00 tip trick at any of the car rentals in Las Vegas? going there for six days in Jan. 2008

[Dick Grayson]

Re: tipping car rental (vegas)

5 bucks if you want a full-size (book economy).

This ain't a hotel that's $100/nite.