I dropped a 07 Camray back yesterday with 46k miles on the clock.
The car was in such bad condition that I made a complaint to the manager. The car vibrated when the breaks were used, and when driving between 40 and 60 MPH there was a whine from the rear wheels.
The returns agent who I spoke to first about the state of the car remarked that 'Hertz are saving money by keeping older cars' - to which I remarked that they were also loosing customers which such bad cars.
The good side to the story was that Hertz took this seriously, and i recieved a $100 voucher, plus a part refund of the non prepaid part of the rental. I only had the car for a day.
Hertz is a quality car rental company, and a car approaching 50K should not be part of their range.