The advantage for the purchaser must be the 10 day test drive. Prices appear comparable with the car supermarkets and their stock may well be ex rental anyway. Mileages of around 40k over two years are, IMO, about right. Used, but no too used.

One downside of the Hertz site is the lack of detail about the vehicles e.g. what kit the vehicle has. Whether the staff are helpful if you call to chat about the car you are interested in could be a minus if you need to travel any distance to view.

Having bought two cars after renting them (although it was pure fluke that I was given them by the rental company), I wholehearted like the idea of this type of long test drive in real world conditions.

It would be even better if they gave you your rental money back if you bought a new model from the manufacturer rather than from Hertz. (Don't Ford own Hertz?)