Like any engineered part, engines and drive trains are manufactured to a defined set of tolerance and these change with temperature due to thermal expansion. Lubricating oil operates differently with temperature, viscosity reduces as temperature increases and performs best when the engine is within its normal operating temperature range.
In a cold engine, the clearance fits are tighter and the oil has a higher viscosity, as the engine warms, oil viscosity decreases and the engine expands giving better clearances, at the optimum temperature everything is perfect.
So you turn up for a test drive, the engine is cold, you proceed carefully, you treat the engine with care, not exceeding 2500 rpm until its warmed through, fifteen minutes or so...... yeah right of course you do. You rag it from the off, its not your car after all so who cares and of course everyone else who's tested it has done exactly the same thing.
And what happens, less lubrication + tighter tolerance = high wear, this might not be a problem, you will probably have higher than average oil consumption, pads and disc's might need replacing earlier, the real problems will only manifest themselves in later life.
My first Z4 was an ex demo, 6,000 miles on the clock when I purchased it, it used a litre of oil every 6k miles, my new car, where I am the first owner, has done nearly 19,000 miles and hasn't needed a top up yet.
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