With automakers breathing down their necks to reduce EU emissions, the diesel engine is slowly dying out. Its market share has declined from more than 50 percent in the pre-dieselgate era to just eight percent in the first ten months of the year. That puts diesels in fourth place among drivetrains, well behind hybrids, gasoline, and even plug-in hybrids. Yes, for the first time, PHEVs are taking out diesel on the continent.
But Audi isn’t ready to retire the TDI just yet. The company has been selling diesel-powered cars since 1989 and even won Le Mans eight times with the TDI endurance racer. It once shoehorned a massive V-12 diesel into the R8 supercar, though it never made it to production. Fast forward to 2025, and there’s a new 3.0-liter V-6 with an electric twist.
Debuting in the A6 and Q5, Audi’s new six-cylinder diesel combines a mild hybrid system with an electrically powered compressor. Although Ingolstadt has offered 48-volt diesels before, this is the first time that the MHEV hardware works together with an electric compressor. The unit is mounted behind the turbocharger and intercooler in the intake tract.
When you floor the accelerator, and the turbocharger has little energy to work with, intake air is directed to an electrically powered compressor. Already compressed by the exhaust-driven turbo, the air is further squeezed before entering the combustion chamber. The result is more torque at low rpm and virtually no turbo lag. Even Audi claims that the latest V-6 diesel offers response comparable to that of a similarly powered electric car.
Photo by: Audi
As for output, the 3.0-liter unit delivers 295 HP from 1,500 RPM to 3,620 RPM and 428 lb-ft (580 Nm). Compared to its predecessor, a maximum boost pressure of 3.6 bar makes it almost a full second faster. The compressor wheel also spins about 40 percent faster, hitting 90,000 rpm in just 250 milliseconds. This translates to a quick response off the line, with the car covering “a good car length” in the first two and a half seconds.
When towing, the mild hybrid system adds a temporary 24 HP and 170 lb-ft (230 Nm). Impressive figures, but how do they translate to the street? An A6 sedan equipped with a V-6 diesel sprints to 62 mph (100 km/h) in 5.2 seconds and tops out at 155 mph (250 km/h). A slightly heavier wagon needs only a tenth more.
Despite matching the weight of the A6 sedan, the Q5 is actually faster. Regardless of whether you opt for the traditionally sized SUV or the sleek Sportback, both hit 62 mph in five seconds flat and share the same top speed as the A6. As impressive as all this sounds, the diagram illustrating the complexity of the drivetrain makes us worry that something might be amiss.
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Source: Audi
But Audi claims we shouldn’t worry because stability has improved over the previous V-6 diesel. Additionally, fuel efficiency is dead. But clearly, this is not a new engine. The “EA897EVO4” codename confirms that this is the latest evolution of a Volkswagen Group diesel that was first introduced in 2010. Before Zuffenhausen had abandoned diesel altogether after the Dieselgate scandal. In fact, EA897 was part of the debacle surrounding emissions-accelerating devices.
Still, Audi insists this latest V-6 is its cleanest yet. It can even run on hydrotreated vegetable oil (HVO), which reduces Co₂ emissions by up to 95 percent compared to conventional diesel. Made from used cooking oil and agricultural by-products, HVO is already filled in diesel cars built at Audi’s Neckarsulm and Ingolstadt plants in Germany.
We’d normally expect to see this engine in the A7, but the big Sportback is unlikely to get the next generation. The future of the A8 flagship is also up in the air. Next year’s Q7 and even more likely the Q9 are going to receive an updated V-6 diesel.
