Next time you’re running close to the deadline for returning a rental car and have to choose between a late fee or being penalized for not having a full gas tank, be sure that you’re using the right per-gallon dollar amount when figuring out which will cost less. According to a new USA Today survey, the penalty for having to fill up a rental car’s tank can now set you back over $9 per gallon.

The paper surveyed this pricing at 13 airports and found Hertz charging $9.29 a gallon, with some Dollar and Thrifty sites charging $8.99 a gallon. At these rates, the penalty for leaving a 35-gallon vehicle with an empty tank could set you back around $325.

USA Today also found that slightly more than half the rental sites surveyed offered pre-paid gas deals that charged less than what you’d pay at a local gas station. However, the article warns that, while you won’t get penalized for returning the car with an empty tank, you also won’t be credited for unused gasoline.

Rental car gas prices hit more than $9 a gallon [USA Today]

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