ITCH4 suggested going to Costco.com instead of autoslash.com. Why not do both? That’s what I have done the last couple of rentals just to make sure autoslash.com can do what I think it can do do. Autoslash has beaten every price I could get. I used to rebook 6 or 7 times but will rely on autoslash to do the work.
One other tip I have. Check rates when you get to McCarron if you haen’t used autoslash. Rates are sometimes lower the day of your rental. Make sure you check the cancellation policy for your current reservation. Some companies are starting to charge cancellation or no show fees.