The hertz Mustang is actually a shelby tuned GT. its one step below the GT 500 and you can't just rent one. you have to sign a long contract that says that any damage done to the car that could in any was be concieved as being the result of aggresssive driving will be paid in full by the renter. Additionally, any performance related damage may or may not nresult in the customer no longer being able to rent vehicles from Hertz in the future.
I was at a hertz center a couple days ago (drove past and decided to stop) and i was asking about how hard ti would be to rent one.