Rotary-piston injection pump: well-proven and up-to-date

The first-ever Audi TDI engine was the 2.5 TDI, introduced for the Audi 100 Avant in 1989 and the precursor of a hitherto unparalleled success story. The newest and best-performing member of the family of cars equipped with a radial-piston injection pump is now once again called the 2.5 TDI, but its badge sports a small red flag: since the end of 1994 Audi has used this symbol to identify the most sporting model in any model line, with the same engine size as the others.

The new engine will be premiered in the Audi A6 and A6 Avant. With a power output of 132 kW (180 bhp) and a torque of 370 Nm all the way from 1500 rpm to 2500 rpm engine speed, it is among the world's leading series-production engines for specific power output, at 53 kW (72 bhp) per litre.

The list of noteworthy technical features to be found on this latest Audi engine is a long and interesting one: four valves per cylinder with centrally located injector, turbocharger with electronically controlled variable turbine geometry (VTG), the latest VP44-S3 radial-piston injection pump with three plungers, capable of achieving a maximum injection pressure of 1850 bar, charge-air intercooling, exhaust gas recirculation, pilot injection controlled by solenoid valve, a first-stage catalytic converter located close to the engine and followed by an oxidating converter.

Whichever of the transmissions is specified with this engine, it always complies with the tough EU III exhaust emission limits.

Capable as it is of accelerating from 0 to 100 km/h in under nine seconds and reaching a top speed in excess of 220 km/h, this new top V6 TDI in the Audi A6 quattro can genuinely be described as a sporting thoroughbred. All the more remarkably, it needs only a miserly 8 litres of diesel oil per 100 kilometres (total consumption figure according to the 93/116/EC test method, giving it an operating range that may well exceed 870 kilometres before refuelling is necessary.

Together with the two 1.9 TDI and four transmission versions of the 2.5 TDI with a power output of 110 kW (150 bhp) in either the A6 or A6 Avant, Audi can justly claim that this superb V6 TDI engine represents a versatile and unsurpassed offer in the midsize car class.