Audi A6/Q5 Diesel: Three-liter TDI accelerates almost like an e-car

The Audi A6 and Audi Q5 model lines will receive the three-liter V6 diesel engine (internally designated "EA897evo4"), proven in the group for years, with some profound modifications aimed at improving consumption and response. To achieve this, engineers have combined the classic hybridization components of a powertrain generator and a belt starter-generator with an electrically driven compressor for the first time. Audi specifies an output of 220 kW and 500 Nm of torque. When starting from a standstill, all three units together can accelerate the Q5 faster by one car length within 2.5 seconds, as Audi further states.

Work on the starting experience

Audi bravely reports that the "starting experience is almost equivalent to that of an electric drive with similar performance." To even remotely keep up with the superior drivability of battery-electric drives, Audi has significantly increased the performance of the electrically driven compressor and the power of the electric motors. Above all, they are intended to support the combustion engine when it has not yet built up enough speed and boost pressure to deliver the required power. 18 kW can be contributed additionally if preceding recuperation processes have charged the lithium iron phosphate battery.

Bild 1 von 5

Audi V6 TDI (5 Bilder)

Classic hybrid components, electric compressor

The belt starter-generator sets the engine in motion with greater force than a conventional starter and can otherwise serve as an alternator. The operating strategy, however, attempts to store as much excess kinetic energy as possible back into the battery in the form of electrical energy. The powertrain generator can do the same, but its main task is to help set the Audi in motion and otherwise allow it to drive purely electrically with the diesel engine switched off. Audi cites examples: "Slow city traffic, when parking and maneuvering, or in flowing traffic on country roads." When starting and overtaking, it can briefly contribute up to 230 Nm of torque, almost half of the engine's torque. During deceleration, this electric motor can recuperate up to 25 kW of kinetic energy.

The electrically driven compressor always supports the exhaust gas turbocharger when it is still building up boost pressure from the exhaust gas's kinetic energy, i.e., "when starting, accelerating out of town, during overtaking, or on the highway," as Audi writes. The maximum boost pressure can briefly rise to 3.6 bar when overcoming the so-called "turbo lag," a value that was considered utopian with conventional exhaust gas turbocharger technology not long ago.

High boost pressure increases torque at low revs and, according to Audi, also enables significantly lower fuel consumption compared to the previous engine generation. And: "While the electrically driven compressor previously only worked in a small operating range, the new generation now operates across the entire speed band." Audi states a combined fuel consumption of 6.1 to 5.3 liters for the A6 and 6.8 to 5.8 liters per 100 km in WLTP.

The V6 TDI is now available for order exclusively with all-wheel drive for the Audi A6 and Q5.

(fpi)