Audi S8

The engine is the 4.0 TFSI V8 in its strongest tune, with the eight-speed ZF. The turbochargers again sit in the vee of the block, with all the heat and all the consequences of neglected oil -- the same weakness as the S6 and S7, except that here the engine works harder.

There is also a much older S8 with a naturally aspirated 5.2 V10, a relative of the Lamborghini Gallardo. If one turns up it is a different car from a different era -- not an earlier version of this one, but a separate purchase with a separate bill.

These cars are often run on tuning software in America, and run without much thought for their remaining life. The software does not show in auction photographs; its consequences do. A proper engine diagnosis before bidding is not caution here, it is the only sensible behaviour.

The front bumper hides an entire system: extra oil coolers, intercoolers and ducting specific to the V8. After a frontal impact not one of those turns up in the yards here -- they are bought new, by part number, at sums that overrun a repair budget quickly.

The brakes are huge as standard. If the car was ordered with the optional carbon-ceramic discs, a single cooked or cracked disc costs what a small city car costs -- one disc, not a set.

And something the A8 does not have: on the S8 the sport rear differential and rear-wheel steering are factory standard. They are why a limousine this size turns like an A4. But after a side impact on a rear wheel, the rear axle's steering rack and its specific arms are not available here and are ordered from Germany or the States.