We booked an Advantage car rental in Las Vegas in Febrary 2013 through CarRentals.com. The initial booked price was really reasonable - but of course we upgraded and paid for a tank of gas up front (dumb). The girl talked me into the gas because we had planned to go to Hoover Dam and she thought we'd go through the tank with the Malibu. We didn't - we used only about 1/2 tank of gas. So don't get the prepaid unless you're planning to drive a full tank full - and don't trust the counter agent's opinion.
The biggest thing I wanted to blog about is the fact that my husband left his pullover windbreaker in the car with his cellphone in his pocket. We checked back twice with the return facility within an hour of dropping it off - once I even walked back to the car with the manager - and the windbreaker and phone were long gone.
It could only have been stolen - there is no other explanation. My husband knows he left it in the car.
I don't recommend using this car rental company. However CarRentals.com does broker some good prices - so I'd still use them.