While working in Cannes our crew has a rental car, and it gets valet-parked every evening at the hotel. In the morning the valet runs out to grab our vehicle (I don't know why he runs, we never tip him) from a parking area down below the hotel's entrance. After a minute or two we can start to hear him in the distance as he rounds the first corner, weaving through a maze of turns and the gauntlet of other parked cars, steadily accelerating until he's 20 or 30 feet away from where we're standing.
At which point he pops the transmission into neutral, and fully and expertly locks the parking brake in the full up position whilst steering through a street racer's handbrake turn. And just before the brake pads burst into flames, the car lurches to a stop at our feet.
Bonne Journée! he says, hopping out. Au Revoir! I say in return.
Ok, maybe a slight exaggeration. But over the past twenty years of renting a lot of cars, riding in rental cars, and observing the operation of rental cars, I can say with some confidence that not owning the car that one is driving can bring out the worst in people. Or from a realist's point of view (mine), it releases whatever restraints are holding back marginally terrible people, allowing them to blossom into their full potential.
People who wouldn't think of slamming their own car's doors? They'll slam a rental car door. Driving on the highway in second gear because you bought the full tank of gas and you need to burn off a few gallons before dropping it off at the rental car center? Completely logical. Hitting speed bumps fast enough to get airborne or to get the distinct feeling that the front axle has detached from the frame? Absolutely! Eating a loosely-wrapped two pound California burrito larger than most people's thighs, in a manual shift rental car with cloth seats? Why not?
Hell is other people, it has been said. So don't buy the cars they've driven.