THE most potent Audi V6 TDI ever to enter production powers executive class Audi models to 62mph in a fraction over five seconds and returns up to 44.1mpg

The knockout punch in a velvet glove comes courtesy of a formidable new 313PS Audi biturbo TDI engine, which is now available for A6 Saloon and Avant and A7 Sportback models.

The new twin-turbo V6 is notable not only for being the most powerful six-cylinder diesel engine ever offered by the Vorsprung durch Technik brand, but also the sweetest-sounding. Available now in A6 models priced from £43,810 OTR, and from £51,645 OTR in the A7 Sportback, it combines trademark Audi TDI refinement with an exhaust-mounted sound actuator that enables it to deliver its mighty 650Nm output to the tune of a distinctly sporting soundtrack.

Slotting in above the single-turbo 204PS and 245PS versions of the 3.0 TDI that already feature in the A6 and A7 Sportback ranges, the latest V6 has a two-stage turbocharger group that delivers a maximum boost pressure of up to 3.2 bar, helping the A6 3.0 BiTDI quattro Saloon to lunge at the horizon and pass the 62mph marker in as little as 5.1 seconds, and the A6 Avant and A7 Sportback to do the same in just 5.3 seconds. An electronically limited top speed of 155mph is common to all versions.

Like the existing TDI engines, the new star performer is backed up by technologies from the Audi modular efficiency platform, including start-stop and recuperation systems and the innovative thermal management system that quickly brings the coolant and oil up to their operating temperatures. With their help, combined economy in A6 and A7 Sportback models is on an equal footing at 44.1mpg – an impressive figure given the high outputs and low acceleration times involved.

Thanks to an innovative actuator in the auxiliary channel of the exhaust system, the BiTDI A6 and A7 Sportback models don't sound like they should be capable of such level-headed economy figures. The actuator system essentially consists of a speaker which imposes a defined oscillation pattern on the exhaust flow and transforms the typical TDI exhaust note into a more sonorous roar that is closer to the output of a high-performance petrol engine.

Without exception, power is transmitted from the BiTDI engine via an eight-speed tiptronic transmission to the latest generation quattro all-wheel-drive system, which features a self-locking centre differential and torque vectoring for optimum traction and stability. A sport differential which distributes power in continuously variable proportions between the rear wheels is also available.