I have seen first hand how rentals were treated and maintained. At least you can carfax a single owner Mustang owned by a teenager. You can't do that with a rental. You won't know how many times it's been in the shop for a new bumper, dings and various other repairs that you wouldn't want on a car that you plan on paying thousands of dollars for.
2012 Mustang GT, Ingot Silver, 6M, 3.73, Brembo.
Whipple 2.9, Flowmaster AT Cat Back 817500.