Be careful. I've returned early with Avis/Budget and had a lot of trouble getting the vehicle returned.

Avoid using any coupon on your rental (even the ones for bonus airline miles or whatever). Their system freaks out if you early return a rental with a coupon. The system will throw an error that prevents the vehicle from being checked in (usually something like coupon terms not met) then the employees have a very difficult time removing the coupon from the contract to force the return to process (it is a difficult process that requires multiple manager overrides and often nobody who is working there knows how to do this or has that level of override permission).

Also do not do a prepaid rate- you won't get any refund for returning early with a prepay.

There are also minimum/maximum rental periods attached to each rate. So don't be surprised to see them re-rate if you try this.

I would suggest, at the time you do the vehicle check out, telling them you intend to return a day early. Just check ....very....carefully.... that the rate you are being charged matches your quote....