The Audi lineup offers a broad choice of diesel engines with four, six and eight cylinders. It begins with the 1.6 TDI, includes the 2.0 TDI and 3.0 TDI, and tops out with the 4.2 TDI producing 283 kW (385 hp) and 850 Nm (626.9 lb‑ft) of torque in the Audi A8 [7.4 l/100 km (31.8 US mpg), 194 g CO2 per km (312.2 g/mi)]. All of these engines combine ample power with groundbreaking efficiency, particularly in the 13 ultra models currently available. The Audi A4 1.6 TDI ultra, for example, consumes on average just 3.2 liters of fuel per 100 kilometres (73.5 US mpg) [85 grams CO2 per km (136.8 g/mi)]. These same figures for the A4 2.0 TDI ultra are 4.0 liters per 100 kilometres (58.8 US mpg) [104 grams CO2 per km (167.4 g/mi)] and for the A6 2.0 TDI ultra with S tronic 4.4 liters per 100 kilometres (53.5 US mpg) [114 grams CO2 per km (183.5 g/mi)].
Audi has further developed the TDI engine continuously since its premiere in 1989. In 26 years, the brand with the four rings has since then continuously increased its lead and established numerous milestones.