I've only rented from Fox once; it was in Denver I needed a car for three days.
They gave me a newish Explorer (I rented something much smaller), with only about three-digit mileage.
I didn't really feel happy flooring the car the whole time going up I-70. Pedal was to the floor and I will slowing down. Just means I'm never renting that car again!
Service otherwise was pretty good. Only 10 minutes to so get my car.