The only catch is that you don't know which rental company you'll get and that your purchase will be final. As which rental car company you'll get, the best answer to that is to research what other people have been getting. Problem of course is that it isn't a guarentee. What a mid-size SUV is, is differant with each company, but they are usually similar. When you get to the airport, you very well could have the choice of 10 differant models, or just one in three differant colors. I hope this helps. ~JS