After spending more than an hour punching in codes at various rental car websites for a ten day trip, I found the cheapest rate using Travelocity! I was looking for a midsize car, using any onsite MCO company. In my original search, combining two codes I found at mousesavers.com, I found the best rate at National. (which suprised me since I usually find the best prices at Dollar). I never tried Travelocity or any of the other travel help sites for cars. But when I was searching for hotel rates, I just tried the rental cars, and oila! Alamo (now onsite at MCO) came up $25 cheaper (all taxes included) - and that was with no codes or coupons!