Late to this party but here is my thought.
Mileage is one but not the only one measure to assess vehicle condition, and therefore its value. There are other factors, such as operating hours, operating environment, market dynamics, etc.
To most layman, mileage is the easiest definition to understand and to assess. I therefore think that clocking is unacceptable given majority of buyers and sellers place such overly reliance on this single measurement.
One of my recent purchase (911 Turbo) has done just under 2,700 operating hours over 12 years and 94,000 miles, registered and serviced in south east England. It was in better condition than a lot of other cars I have seen with sub-50k miles or living in Scotland (or both).
pete g wrote:Take it from an engineer... its not only Eng items belts etc, a 150k car is just about worn out in all respects.
The front will be gravel rash with FOD
The suspension will be loose and soggy, the seats will have been sat in and god knows what else done in them 5 times more than a 30k car. The gearbox/diff/bearings and bushes will be hanging...
It been exposed to 5 times amount of salt and shite...
I would disagree that all 150k cars are essentially scrap. Personally I place more reliance on operating hours and operating environment than mileage.
I am currently running a MR2 with 191k miles and with the exception of stone chips, the engine, gearbox, suspension, etc. all are tip top. Even the specialist who only looks after Mark 2 MR2s commented that while he only likes the Turbo version, my non-Turbo is significantly faster and better to drive than any other non-Turbo MR2s he has driven.
Given it gets driven hard on drive days and track days, the engine and gearbox are still original. All suspension components got refreshed every 60k (springs, dampers, bushes, mounts, etc.) so it is on its 4th sets of suspension. Everything still work (a/c, all electrics, etc.). I have first refusal from other customers at the specialist if I decided to sell it, despite the mileage.