Having spent a career in the automobile industry - working my way up from parts runner in 1974 - to management for many, many, years before my retirement in 2007, I will not say that there aren't dealership employees who abuse vehicles, however I will say that if I witnessed an employee abuse a vehicle - they would be fired on the spot.
Also I must add that, yes, you can "abuse" and "damage" modern cars. Those who think otherwise are deluding themselves, and in my opinion posting misleading information on this site.
I am middle age and rent quite a bit for business. I pick up at airports. Sorry it's a myth. I drive absolutely perfect til the return. The logic is you need to make it to a trade show, to a hotel, and not break down for a return flight. The last 3 miles is irresistible; I really get on it, and I mean hard. At least I am honest. Maybe the extra wear and tear is covered by things I have left in the car at times. Or the phone call the rental company makes when you drop off and there is no final inspection walk around. So they hit the credit card for the scuff or dent if you don't take the extra insurance.
I know a guy once that was so late he slid into the rental return lot sideways. The coat hangar dropped out of the ceiling in the back of his luxury sedan upgrade.
Actually, the only time I may agree on your rental comments is when a family may rent with kids in a car. Even my wife has a lead foot. Who's fooling who?
The salesmen and sales managers who drive their demos home are now few & far between. Other than dealership owners, those perks are long gone for the most part.
Coming up through the ranks myself, back in the day when demos were more common, I can say personally we certainly did not beat on our demos as we valued our jobs. Again, not saying there weren't bad employees who might have, but they would be unemployed if they worked for me.
Having worked for a major dealership, I can assure you no rental car ever faces the kind of brutal use a brand new car on the lot goes through. I have seen burnouts, speed bumps taken flat out and even body damage from hitting other cars on the lot. One of my buddies wrecked his demo. In no case was anybody fired. The cars were just repaired and sold to unsuspecting customers. I'd take a rental any day.
The only possible downside to a rental vehicle is possible excessive brake wear, because most of the driving is done in city traffic. I bought a gorgeous loaded Pontiac from a rental company in 2003. It had 30,000 miles on it. The car was perfect in every way except for premature brake wear. I ended up replacing the front brake pads at only 70,000 miles, which for me is way too soon.
I am also a member of a performance car club, and one of our favorite activities is burnout contests where we see how far we can keep the tires smoking. I have done burnouts with my own car, and except for a tiny bit of tire wear, it hurts nothing. Once a tire breaks loose and starts spinning, there is virtually no load at all on the engine or drive train, and the rev limiter ensures that the engine can't over rev.
I'd never hesitate to buy a car that I knew had been driven aggressively. Rapid acceleration just does not hurt a car. Neither do sliding turns or sudden braking. Cars are engineered to handle all sorts of driving. Just watch some of the Ford torture test films sometime.
So if one of your buddies in the performance club accidentally shifts into a low gear on a fast upshift and over-spins the engine, does he give you the bill because it overshot the rev limiter?
OP - "Once a tire breaks loose and starts spinning, there is virtually no load at all on the engine or drive train"
I'm sorry, but what you said is definitely not true, unless you are on ice.
The discussion about rental cars has strayed ridiculously far afield. Virtually all rental cars are automatic, so accidentally downshifting to a lower gear is not a possibility. In addition, most rental cars are front drive with moderate sized engines, so wheel spin is highly unlikely. Since all modern cars are equipped with rev limiters and devices that make it impossible to shift into reverse, park or low range while driving at any speed, it's virtually impossible to damage an engine or trans-axle that way.
With regard to wheel spin in rear drive cars especially, the greatest amount of stress on the drive train components occurs at the instant the tire (or tires) break loose. After that the spinning tire generates heat and also heats the pavement. This has the effect of lessening the force between the pavement and tire. As the tire continues to spin, the car moves forward until eventually the car is moving fast enough to start matching the speed of the spinning tire. During the time the tire is spinning, there is far less stress on all drive train components than there is under moderate acceleration with no wheel spin. The only harm done is a tiny amount of wear on the tire. Of course cars with posi-traction will be exerting twice as much stress on drive train components as cars without it, but still less force than under moderate takeoffs with no wheel spin.
The following is a direct quote from a new domestic car owner's manual regarding new car break-in periods:
"brief bursts of FULL THROTTLE acceleration, within the limits of local traffic laws, are BENEFICIAL."
The manufacturer ought to know their own products.
Since you belong to a performance car club, I suspect there are sports cars there, not former automatic rentals... Maybe 6 speed manuals and the like do the burnouts. If I took my car into the dealer under warranty, I wonder if they would have an issue. I was doing burnouts in my club and the piston snapped; fix it at no charge for me!
I would be hard put, to put my thoughts and comments observing a Camry doing a wheel spin at a major intersection. I have rented and did not find myself enamored enough to run out and buy one for personal use. It's very bland. I am sure that's what many want. I hope none buy one for street exhibition purposes and jack rabbit starts. But there's a first for everything I suppose.
Where is the part about slamming on brakes or using the parking brake to slide sideways into a turn?
If the brake isn't applied for too long and the car is allowed to eventually match the pace of the spinning tyre, then yes I know where you are coming from; I was kinda talking about stand-stills, but anyway.
If the throttle was suddenly lifted while doing the burnout, will the tyre keep spinning because there is "low friction"? I'm pretty sure the tyre will stop almost instantly, indicating the amount of force required by the engine/drivetrain to keep the tyre spinning. I would question that this activity places less stress, yet alone FAR less stress, than moderate take-offs with no wheel spin.
Oh and regarding full throttle acceleration being beneficial during break-in periods - which manual is that from, a Kia? LOL.