First, there are several car rentals on site, not just dollar. IIRC, Avis, National, and others are on site. The ones off site can be cheaper, shop around. You can use the Entrtainment book for car rental perks, and the book can pay for itself in Orlando if you go off WDW itself. If you stay at WDW and eat all your meals there and go nowhere else, save your $25.