With the European Union clamping down on carmakers to reduce emissions, the diesel engine is gradually fading away. Market share has fallen from over 50 percent in the pre-Dieselgate era to just eight percent in the first ten months of the year. This puts diesel in fourth place among powertrains, far behind hybrids, petrol and even plug-in hybrids. Yes, for the first time, PHEVs are outselling diesels on the continent.
But Audi isn’t ready to retire the TDI just yet. The company has been selling diesel cars since 1989 and even won Le Mans eight times with a TDI endurance racer. It once put a huge V-12 diesel in the R8 supercar, although it never went into production. Fast forward to 2025 and there’s a new 3.0-liter V-6 with an electric twist.
Audi’s new six-cylinder diesel debuts in the A6 and Q5 and combines a mild-hybrid system with an electrically driven compressor. Although Ingolstadt has offered 48-volt diesels before, this is the first time the MHEV hardware has worked with an electrically powered compressor. The unit is mounted behind the turbocharger and intercooler in the intake tract.
When you step on the accelerator and the turbocharger has little energy to work with, the intake air is routed to the electrically driven compressor. The air has already been compressed by the exhaust-driven turbo and is further compressed before entering the combustion chamber. The result is more torque at low speeds and virtually no turbo lag. In fact, Audi claims that its latest V-6 diesel offers response on par with a comparable electric car.
Photo by: Audi
In terms of power, the 3.0-liter engine produces 295 hp at 3,620 rpm and 580 Nm (428 lb-ft) from 1,500 rpm. Compared to its predecessor, the maximum filling pressure of 3.6 bar builds up almost a full second faster. The compressor wheel also spins about 40 percent faster, reaching 90,000 rpm in just 250 milliseconds. This translates into a sharper response off the line, with the vehicle covering “a good car length more” in the first two and a half seconds.
When driving away, the mild hybrid system temporarily adds 24 hp and 230 Nm. Impressive numbers, but how do they translate on the road? An A6 Sedan equipped with the V-6 diesel sprints to 100 km/h in 5.2 seconds and reaches a top speed of 250 km/h. The slightly heavier car only needs a tenth more.
Despite matching the weight of the A6 Sedan, the Q5 is actually faster. Whether you opt for the conventionally shaped SUV or the sleeker Sportback, both will hit 62mph in five seconds and share the same limited top speed as the A6. As impressive as all this sounds, the diagram illustrating the complexity of the powertrain would make us worry that something could go wrong.
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Source: Audi
But Audi claims we don’t have to worry, as durability has improved compared to the previous V-6 diesel. In addition, fuel efficiency has increased. But to be clear, this is not an entirely new engine. The codename “EA897evo4” confirms that this is the latest evolution of a diesel from the Volkswagen Group that was first introduced in 2010. It even powered certain Porsche models before Zuffenhausen abandoned diesel completely after the Dieselgate scandal. Indeed, the EA897 was part of the debacle surrounding emissions cheating devices.
Still, Audi insists this latest V-6 is the cleanest yet. It can even run on hydrogen-treated vegetable oil (HVO), reducing CO₂ emissions by up to 95 percent compared to conventional diesel. HVO is made from used cooking oil and agricultural by-products and is already used in diesel cars built at Audi’s factories in Neckarsulm and Ingolstadt in Germany.
Normally we would expect this engine in the A7, but it is unlikely that the big Sportback will get a next generation. The future of the A8 flagship is also up in the air.
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