Buying a used Porsche 928

Buying a 928 yourself? Wunderbar! My advice is to find a car in the very best condition possible. The money you spend now will be saved at least twofold later because the true cost of rare, complex, old cars like this are maintenance, not purchase price. Get a pre-purchase inspection (PPI) of any candidates by a recommended 928 mechanic before your buy. Keep a particular eye out for the following items.

Timing belt service
The 32-valve Porsche heads employ an interference design such that if the belt breaks, the engine could be severely damaged. Porsche recommends the T-belt be changed every 60K miles. Most mechanics recommend 45K intervals. As it is rather expensive (upwards of $1,500) make sure the car you are considering has had it done recently.
Faulty climate control systems
Symptoms include poor A/C performance and intense heat when the temperature selector is moved even slightly off full-cold. This can become expensive quickly.
Vacuum lines (see faulty climate control above), coolant hoses and oil seals all leak horribly on a car that has not been driven in a while. This is particularly common on the exceedingly complex 928.
Aligning a 928 is not a trivial matter and special consideration should be taken by one knowledgeable. Most notably, poorly aligned 928s will have too much negative camber (great for road racing, bad for street driving) and completely wear out the inside treads before the outsides even begin to show wear. The problem is that the springs do not settle after the car has been lifted. It needs to be driven about ten miles to settle down again.