While most decent AWDs will make come back with a better non prepaid rate for full size or below, just thought I'd post this for everything else. Usually the prepaid rates aren't discounted any further.
Must use an AMEX card to pay, and you will receive 5% off the lowest prepaid rate. Couple this with the MUWA028 $35 off a week coupon and in many cases, you've got a good deal. (especially for vehicles not typically discounted much in most AWD rates)
https://www.avis.com/car-rental/profile/go.ac?S692200
Valid for rentals picked up between 10/23/2013 - 12/31/2013.
$25 cancellation fee and $100 no-show fee. If your flight gets delayed or cancelled, call reservations and they will waive the fees.