Yeah, this. The old days of selling known lemons and being able to charge any price they want for it all long gone, thanks to the Internet. It's why the dealership I used to work for sometimes would not certify a car that qualifies for it: there was a fee on our end to do so, and it was particularly high for a six year cert versus a five year and would push the car well above the market price. At the end of the day, dealers just wanna move cars.
Most of the people I know beat on them. Things like fast acceleration, tailgating, running over stuff, and a lot of increased wear and tear on systems you won't see. This may not be as problematic today with your standard sedan. I would avoid suv type cars or pickups especially with 4wd. The transmissions end up going pretty quickly and you probably won't see it coming from a test drive.
If by fast accelerating you mean red lining it, I agree with that. But I put the petal to the metal all the damn time and I grew up with a brother who raced all of his trucks and just fast acceleration doesn't do it. Tailgating is not a problem for the next owner. If running over something causes damage I will notice as either there will be damage around the wheel wells or the front end will be out of alignment or I will hear a banging or see a dripping everything else is fine. Again using the 4wd to go mudding unless you are red lining or flooding it with water isn't going to hurt the truck. Transmissions fail for a number of reasons. Only things I agree with, even though you weren't explicit, is the red lining. But that goes with any used car, just as possible flood damage does.
These are activities which cause a lot of wear on transmissions and the engine. This may not be as much of a concern for newer engines, but when I grew up this lowered the lifetime of these things, and the stresses effected other systems also. It is why city driving eats up your car faster than highway driving. Knock on wood, but my cars last a lot longer the less I beat on them. The newer engines and fuel injection systems are probably a lot better at dealing with these things. Plus, some cars do not seem to let you beat on them. The economy Toyota's just do not seem to respond at all if you try to push them too far. Perhaps that is why they last so long. I know too many people who won't bother to swerve much for anything if it is not their car. Modern cars are much better with this having a reflective plastic undercoating on a lot of models, but you can still screw things up. I lived in snow country. I have owned many 4wd suvs, and have known many people with pickups. The transmission goes much quicker, and not because of mudding. Awd systems seem to do better. I think it is the reality you are adding extra gears and you are also putting more strain on the transmission due to weight. It was not uncommon to burn through a transmission in less than 100k on a snow vehicle in my area. That is not with a lot of hard driving either. I think that is why suvs in non snow areas often lack the 4wd because the regular transmission does not eat itself as quickly. Flood damage may be a problem. I am not too familiar with it.
And any of that can be caused by a person who knows they'll be trading in the vehicle in a couple of years. I would bet more of the rental car drivers are good to the vehicles rather than bad. And the bad only has the car for a couple of days to a week. Where as you pick the wrong used vehicle where the person knew they would be trading in... Still not a reason not to buy rental. In fact it's less of an argument as the probability of getting many bad drivers is smaller compared to one bad driver over a long period of time. Also I live in mud country not snow country. 4wd is rarely used here as most live with paved roads. It's why you don't buy from a farmer/rancher or buy fleet trucks. But really only fleet trucks come up for sale. And they are busted all to hell. In that regard yes 4wd break quicker, if they are being used. They're really just for show in OK.
I don't know that I would buy a used rental car. When one is in a rental car, it will be driven as such. People are just hell on them.
FTFY I've never had the desire to drive stupid with a rental. Not the least of those reasons being none of the Toyota or Fords I've gotten come close to the power of either MINI I've owned, but also because I don't want to pay extra for damages.
If anything, I'm probably much more careful in a rental. One, it's an unfamiliar car, and I'm not as comfortable driving it. Two, I don't want to deal with the hassle if I bang it up. (I did actually get into accident--someone rear-ended me--when I was driving a rental care once.)
I scraped the bumper of one just as I was bringing it into the airport. I wassling an illegal u-turn and didn't realize the nose was so big. I mean, if it had happened a day begore....but I was RIGHT THERE Luckily, I was only out $300 dollars for that scraped bumper.
How so. Nobody can tell me how they drive a rental that I can't tell? Also how different do they drive from someone who knows they'll be turning that car in, in 3 years no matter what or so many miles no matter what? You are gambling on someone doing appropriate maintenance no matter what. At least with a rental company, with a good rep you have some idea.