21. C7.5 Audi S6

The Audi A6 and S6 of the C7 generation combine understated styling, a beautifully assembled interior, excellent long-distance comfort, and Audi’s confidence-inspiring quattro all-wheel drive. Sold in a wide range of configurations worldwide, the C7 A6 could be equipped with everything from a 2.0-liter turbocharged four-cylinder to a supercharged 3.0-liter V6 and diesel options, while the performance-oriented S6 featured a 4.0-liter twin-turbocharged V8. These cars aren’t especially light or nimble, but they’re exceptionally composed at highway speeds, making them excellent long-distance and all-weather vehicles. The cabin remains comfortable and spacious even by modern standards, although the infotainment system and pop-up display are beginning to show their age.

Like many German luxury cars of this era, reliability depends heavily on choosing the right engine and maintaining it properly. Common C7 issues include aging air suspension components, electronic faults, water intrusion around the comfort control module, carbon buildup on direct-injection engines, and various cooling and oil leaks. The 2.0-liter TFSI has a history of piston-ring, PCV, and timing-chain problems, while the TDI models bring additional complexity through their emissions systems and fuel-injection components. The supercharged 3.0-liter V6 paired with the ZF 8-speed automatic is generally regarded as the strongest all-around combination, provided it receives regular maintenance. The S6’s twin-turbo V8 is remarkably powerful and rewarding, but its high-heat “hot-V” design makes maintenance particularly important; buyers should verify that the turbo oil-screen recall has been completed on affected models. Overall, a well-maintained C7 A6 or S6 can be a remarkably durable luxury car, but repair costs are considerably higher than those of comparable Japanese vehicles.