I rent from Enterprise about twice a month and this is par for the course. I agree that they probably come out "ahead" for most customers, but not me.

That's because of the thing called the "odometer". You measure how many miles you've driven, then calculate how much gas you've used. (Most rental cars seem to get in the low to mid 20's mpg, so it's easy to figure out roughly how much gas you've used. Obviously SUV's are lower, subcompacts higher) I always subtract a half-gallon for good measure. Then, at the gas station, you simply watch the pump until you hit the magic number.

I'd bet that 75% of the time, I come out "ahead". (i.e. returning it with less gas than was in it when I picked it up).

Also, I must add that the Enterprise agents I deal with routinely give me the benefit of the doubt. That is, they round down to the nearest hash mark on the gas gauge when checking it out, and round up when checking it in.

All this being said, I do think that rental car companies should rent it out with a full tank, simply for the convenience of the customer. A full tank can make the difference between getting somewhere on time or having to fill up first.

I would also add that my last rental from Avis also did not have a full tank. But that was even worse than Enterprise since the rental contract said it had a full tank and I had to go back to the counter to get them to correct it.