The AUDI A6 (1997-04) 4DR SALOON 2.5 TDI 163 SPORT is a large, four-door diesel saloon from the premium end of the UK used-car market. It offered a spacious, refined alternative to mainstream family cars, competing with period BMW 5 Series and Mercedes-Benz E-Class models. Its restrained styling still feels purposeful. The mycarcheck.com picture is based on six look-ups covering three distinct VINs, so it is a small sample rather than a definitive reliability guide. Those checks show an average private-sale value of £1,000, around 124,000 miles recorded and two previous keepers. The average annual mileage is 2,000, a figure worth checking against the car’s history. With its diesel character, comfortable cabin and composed motorway manners, this A6 suits commuters and drivers wanting a roomy, understated car; it can serve a family. Compared with rivals, age and maintenance matter most, so check service records, condition and mileage before buying carefully.