Introduced in 2001, the Audi A4 Avant B6 represented a major technological leap over the B5, sporting a stiffer body, Peter Schreyer's crisp Bauhaus-inspired styling and increased cabin space. The benchmark powertrain remains the legendary 1.9 TDI Pumpe-Düse producing 130 hp (AVF) or 115 hp (AWX)—a bulletproof unit with a timing belt that mandates renewal every 120,000 km or 6 years. Conversely, the newly introduced 2.0 FSI was Audi's first direct-injection petrol engine; without fuel washing over the intake ports, it suffers severe carbon deposits on the valves that necessitate walnut blasting around 80,000 km. Regular Audi A4 maintenance keeps these engines running cleanly.