More and more airports are adopting the off site car rental center that, in my opinion, is the best concept since sliced bread. It frees up much needed room at the airport for their main operations serving the passengers and guests. McCarran is no exception.
The major rental companies reside on the main floor while the cheaper Fox rental cars are located in the lower level. The Fox rental cars are definitely the cheapest cars you can get for less than $10 a day but you get the most basic car with manual locks, no alarm, roll up windows but thankfully automatic transmission and some A/C. If you can stand not having those conveniences, then try Fox out. If not, Thrifty and Enterprise have been good for me! Enjoy the convenience as there is one less thing to work about on your travels!