Check you receipt carefully to make sure Avis didn't think you drove less than 75 miles, even if you know you drove way more.

Just a few days ago at LAX, I returned a weekly rental where I'd driven 177 miles. At the checikin, they gave me a "receipt" that says "check-in failed, go to counter". At the counter, they printed a receipt within a minute or so. But when I walked away and read it, I saw they only thought I drove 77 miles, because they keyed in the "mileage out" wrong (1000 high).

I now shudder to think that if they'd made this mistake on a car that I'd driven 173 miles, they would have not only gotten the miles driven wrong, but as a result would have charged me for gas!

So always check to see that they didn't accidentally calculate that you drove less than 75 miles, and charge you as a result, even when you know you drove signficantly more....