Since then, Audi has introduced numerous production, concept and race cars powered by TDI engines. The automaker has even enjoyed a string of successes in the prestigious 24 Hours of Le Mans with the technology. Now, to mark the 25th anniversary of TDI technology, Audi is celebrating with the 2014 A7 3.0 TDI competition.
The special edition is only confirmed for the European market at present and is powered by a 3.0-liter TDI V-6 delivering 326 hp and 479 lb-ft. To help maximize performance, the engine also features an overboost function that lifts output by 20 hp for a brief period, and its peak torque arrives at just 1,400 rpm. The A7 3.0 TDI competition will sprint to 62 mph in just 5.1 seconds and averages about 38 mpg on the European combined cycle.
The basis of the vehicle is the updated 2015 A7 model. Special touches include custom 20-inch wheels, red brake calipers, an S line exterior package, Valcona leather trim, and aluminum and Beaufort wood dash accents. An eight-speed automatic transmission is standard.
Audi electric turboEnlarge Photo
The system is essentially a sequential twin-turbocharger setup where the smaller of the two turbos uses an electric motor to help spool it up quickly at low revs and then by way of a valve switches to conventional exhaust gases at higher revs. A single turbocharger system has also been developed.
The electric motor is rated at about 10 hp and can get the turbo spinning at speed in just 250 milliseconds. The energy required to drive the electric compressor is largely generated by recuperation during coasting phases, so that the end effect is essentially neutral with regard to energy consumption.
According to Audi, the technology not only aids off the line acceleration, but it also maintains charge pressure when entering a corner, when the driver is likely to be braking and revs drop, allowing for a quick exit at the other end. It also eliminates the need for constant downshifting, thus allowing engine revs to remain low during normal driving.