Another post reminded me of a mistake I made several years ago with a car rental, even though I already knew better.
Never say yes to the rental company topping off the gas tank for you.
Many rental companies will ask if you'd rather have the convenience of not worrying about filling the car's gas tank before you return it. Always say NO!
Also, always make sure the tank has the level of gasoline specified in your rental agreement before you return the car to avoid any charges for the rental company's gasoline costs.
In my incident, I didn't use the car as much as I thought I might need to during the last day of my visit and returned the car to the airport with nearly a full tank of gas. Even though it would have been fine, otherwise, I was still charged for the fillup.
It wouldn't have been so painful if they had topped off the tank and had charged me for actual gasoline used, even at their inflated gasoline prices, but I was charged for a full tank of gas from empty. To make matters worse, I was charged for 18 gallons of the rental agency's higher priced gasoline. The car's tank had a specified limit of only 11 or 12 gallons. I was cheated on several levels. They made more profit from my fillup option than from the weekly rental on the car.
Never say yes to having the car rental agency fill your tank for you!
Just say NO!
Enjoy!