Never buy a car from Enterprise. My Grandmother bought one when I was a kid and it really was a clunker.
I bought a '02 Taurus from Hertz in 2004 with 25k miles on it. I still have my '02 Taurus and it now has 133,000 miles and is still going.
At one point in time my family had 5 Ford Tauruses. All of the Hertz rentals at one point in time. All of them were daily drivers for my parents, and brother and sister. The only problems we had were known issues with early high mileage Taurses.
Different rental companies treat their cars differently, and also different rental companies attract different types of people who rent their cars. What is their demographic?
I don't work for Hertz, but all the cars we bought and have rented have been in good working order. The only problem I have with renting cars is that you soon learn what you want to buy, and what should have never made it off an assembly line.
I rented a '08 Toyota Corolla on my Honeymoon, and with both my wife and I and a BUNCH of luggage that thing had some get up and go! I went around 400 miles on 3/4 tank, and that thing has a 13 gallon tank. Alas... my car is almost paid off.