i think that cars like the M3 are like race horses.
If you take a race horse and make it give horsey-rides to kids, sooner or later, it will go crazy or will wither and die.
same thing here.
so far, touch wood, i've not had any problems with my M, and on occasion i've driven it like, i think, it was meant to be driven (being thrashed is a subjective definition). my car is unmodified in terms of engine, suspension and brakes. i find that the car feels better after a long hard drive.
as yes, as satinghostrider has commented, my windscreen looks like the constellations. paintwork is not as bad cos i put on protective films.
stonechips are not an indicator of the mechanical condition of the car.
driver's side bolster worn, probably means it's a daily driver with an owner who either has a big ass (like me) or likes to sit close to the wheel.
having said the above, please do ensure that the car is accident free etc etc...
Agree with edlms. M3 engine runs better the harder it works. It feels smoother and more responsive after a recent drive that went up to about 250km/hr. I would treat stone chips as souvenir from driving experiene. They can be avoided by putting some sort of plastic film on bumper.
Besides stone chips, I still have memorable dead insect stains/scratches and also a bird's head-on-bang claw marks on my wind screen, accumulated from my frequent NSH runs. Everytime I wash my car, I make it a point to not remove those souveniors. Its like my car's curriculum vitae.
Without these and stone chips, I think I need a new account name like Ahguadriver instead of Ahbengdriver.
I have stone chips, had my windscreen also replaced from starry trips from NSH drives.
I would watch out for other issues like engine noises, rattling etc. The later model M3 S54 engines are pretty bomb proof. Except you have to have a check on your lifters/valve shims etc at inspection 2 for calibration.
I am usually more wary of a car with a nice coat of paint, then one with aged stone chips.