You can keep your existing reservation. If you return early, it will most likely be prorated and you'll get back one day of credit, but it's hard to be more specific without knowing the actual dates. Regardless, the worst that will happen is that you'll return a day early and pay your original rate.

All of that said, next year is a loooong way away in car rental terms and lots can change between now and then. Here's what we highly recommend:

1. Track your existing reservation with AutoSlash.

2. Once you receive the tracking confirmation email from us, reply to it and say, "As per AutoSlah's advice on Flyertalk, I'm letting you know that I plan to return the car one day early, so please revise my return date on the tracking request from MM/DD to MM/DD. This way, we're searching for better deals on your actual planned return date as opposed to the one on your existing reservation.

Hope this helps. We look forward to saving you money on your rental!