Avoiding the sting of those hidden automobile rental feesGasoline costs nearly $4 per gallon average in the U.S. today. But did you know it will cost more than double per gallon needed if you do not return the rental with a full tank? Don't let this and other "hidden" fees burst your budget. Go to the rental car counter armed with knowledge and conserve.Rental car gasoline at $9.29 per gallonA recent USA Today survey of vehicle rental corporations at 13 large United States airports found that Hertz is charging $9.29 per gallon to top off gas tanks, while Dollar and Thrifty charge $8.99. If a customer pays the rental company ahead of time, the price goes down a lot, but this is one way consumers' get money stolen by rental corporations all the time.