The second-generation Audi A6 (C5, Typ 4B) marked a major turning point for the four-ring brand. With its aerodynamic design inspired by the Bauhaus movement (Cd of 0.28), it propelled Audi into the big leagues against the BMW 5 Series E39 and Mercedes E-Class W210. Available as a sedan and a wagon (Avant), it also introduced the 'Allroad' adventurous variant in 1999. While its interior finish quality and Quattro all-wheel drive (Torsen) remain benchmarks, this generation is also sadly famous for the introduction of the 'Multitronic' continuously variable automatic gearbox, a source of ruinous breakdowns, and for major design flaws in the early V6 TDI engines. A restyling (facelift) occurred in mid-2001, bringing aesthetic touches, new engines, and reliability corrections.
The Audi A6 C5 is a car with two faces. It can be a formidable, economical, and indestructible flagship if you opt for a 1.9 TDI 130hp with a manual gearbox. Conversely, it can turn into an absolute financial black hole if you fall into the trap of a 2.5 TDI 150/180hp (first generation) coupled with the disastrous Multitronic gearbox. In gasoline, the 1.8T and naturally aspirated V6s are good choices, provided you accept the cost of timing belts. Prioritize buying based on condition and service history, and thoroughly inspect the front axle and the absence of water ingress.