The car rental center is PHX's satellite service center for car rentals. There are numerous car rental agencies located here with a multitude of websites to rent through, but the main reason for this particular review is related to finding it, especially upon return! This review does NOT reflect my feelings about the car rental service that I actually used to rent the car.
The center itself appears quite new. There is a huge garage housing the rental cars and a level of the building dedicated to providing service to customers. The center is about 8-10 minutes FREE SHUTTLE from the airport and each airport terminal provides a shuttle to the single center. Upon returning your car and heading back to the airport, just be sure you've identified the correct terminal that you need the shuttle to take you. From return to arrival at the airport, give yourself 30 minutes of fluff in case the shuttle is not there right away.
The signage to get into the car rental center really sucks. At night there is a serious lack of lighted signs with text large enough to read. Be aware that the address of this center is at 1805 East Sky Harbor Circle South and you're looking for signs for "car rental return."
If you're returning from south of Phoenix, you're on the I-10 heading West. You want to take Exit 150B to South 24th Street. Take a Right at the end of the ramp onto S 24th. At the first light there is NO SIGN HERE!! but you need to take a Left onto Sky Harbor Cir S. Keep your eyes open! Your next turn is to the left. Here there is a TINY SIGN that says "Car Rental Return" and there is no lighting for this sign!
The facilities are clean and the shuttles are frequent enough. Good luck!!