I haven't heard of it. Do you have AAA or a Sam's Club/Costco membership? You can search car rental discounts there too.
Here is what we are doing for our December trip. We are taking a cab to an Enterprise location (at the Westin) and then renting the car there. Then returning it to the Airport location. We got a rate that was MUCH cheaper than renting at the Airport (about $200 cheaper), but we still get to drop off at the Airport. We just had to be sure to mark in that we were returning at the Airport as a different location.
