All rental car companies seem to have a different idea from mine of what exactly a 'full size' car is. There are no industry standards among rental car companies and what they call 'full size' usually looks more like a 'compact' car to me. Be sure to check their website for pictures/examples of the specific type of cars in the various categories to avoid surprises based on what you think you are reserving. The actual size of what is practical for your vacation depends on how many people are traveling and how much luggage you will have. If your party and their luggage won't fit in the vehicle, then the supposed savings won't mean much.