V6-powered Audi RS4 and RS5 will bring V8-matching thrills

When it’s revealed in production form later this year – potentially as early as the New York Motor Show next month – the 2018 Audi RS4 will be returning to its roots after enjoying a decade of atmo V8 power by reverting back to a turbocharged six-cylinder powerplant.

It’ll be the same 2.9-litre turbo twin-turbo V6 as used by the just-unveiled RS5 coupe , and with a stout 331kW and 600Nm of power and torque it’ll have the same amount of power as the outgoing 4.2-litre V8, but with a huge 170Nm increase in peak twist.

But will it be as thrilling as Audi’s now-extinct atmo V8?

The head of Audi Sport, Stephan Winkelmann, seems to think so. Asked whether the new RS-tuned 2.9-litre V6 would deliver on the emotional expectations set by its naturally-aspirated predecessor, his response was succinct:

“It has to be, and it is,” he said.

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And Winkelmann should know about stoking the coals of automotive enthusiasm. Before joining Audi Sport in March 2016 (then known as Quattro GmbH), Winkelmann spent 11 years as President and CEO of Lamborghini. If being top dog at an Italian supercar specialist doesn’t teach you how to make cars that excite the soul, nothing will.

“If it would not have been the case we would not have opted for doing it,” Winkelmann continued, while being careful to note the reasons why the high-revving V8 was replaced in the first place: emissions.

“It is clear that saving CO2 is one issue which is important, so the connection between ‘sportivity’ and sustainability is an important one and has to be credible.”

However while Winkelmann was adamant the V6 would provide plenty of excitement, he squashed rumours that the same engine would find its way into the Audi R8 supercar - that particular model will remain a V10-only device.

It’s a tough ask for a turbocharged V6 to match the visceral appeal of a V8. With no turbos muffling the exhaust note, the bellow of an atmo V8 is always going to have a harder edge and more appealing sonics. Plus let’s face it: V8s almost universally sound better than V6s.

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The dearly-departed V8 was also an exceptionally high-revving unit. The fuel cut came in at a stratospheric 8250rpm. Its six-cylinder replacement, by contrast, redlines at a mere 6800rpm. Engines tend to sing a better song the harder they rev.

And then there’s the question of response. With 1.3 litres of less capacity the RS4’s new V6 would naturally have lazier throttle response than the bigger V8 of the old model. Turbos may compensate for the V6’s smaller displacement and enable it to outgun the 4.2’s torque figure, but they need a moment to gather their breath. Turbo lag is nowhere near as glacial as it used to be these days, but good luck finding something turbo with the sharpness of that 4.2 V8’s accelerator.

Winkelmann’s confidence is reassuring, but will the 2.9-litre V6 adequately replicate the 4.2-litre V8’s adrenalin-inducing character?

We’ll find out when we drive it for the first time later this year.