BMW M6 Gran Coupe vs Audi RS7 Sportback

Only the most powerful and exclusive Audis get to wear the hallowed RS badge. Yet the brand describes the latest addition to its ever-expanding range as “the most seductive model in Audi RS history”. 

• BMW M6 Gran Coupe review 

• Audi RS7 Sportback 

The new RS7 Sportback combines the 552bhp twin-turbo V8 of the RS6 Avant with the sleek A7 body to create a luxurious four-seat coupé with supercar performance. It’s not the only upmarket, four-door coupé with a hugely powerful engine, because BMW has shoehorned the 552bhp 4.0-litre V8 from the M5 supersaloon into the sophisticated 6 Series Gran Coupe. But while the Audi is four-wheel drive, the BMW features a rear-wheel-drive layout that promises greater driver thrills.

What our contenders have in common are eye-watering prices that wouldn’t look out of place on a bona fide supercar. So which one of our fast four-doors better justifies the cost?

Head-to-head

Engines

The pressure to make engines ever cleaner and more fuel efficient has created a trend towards smaller capacities – which means that the days of the V8 may be numbered. Thankfully, BMW and Audi haven’t abandoned them just yet. These 552bhp turbos are epic – the Audi’s 4.0-litre has 20Nm more torque, but the BMW’s 4.4 generates its 680Nm peak torque output 250rpm sooner. Both deliver scintillating performance and tuneful soundtracks.

Cylinder shut-off

The RS7 gets Audi’s cylinder shut-off tech. This means the engine runs as a four-cylinder at low loads. Active engine mounts isolate extra vibrations, so you hardly notice it. Like the BMW, it also has fuel-saving stop-start.

Putting it on the road

Channelling more than 550bhp on to the road is a challenge, but with its quattro all-wheel drive and sports differential, the RS7 has the upper hand in terms of traction. The set-up features a standard 40:60 torque split, yet 85 per cent can be sent to the rear axle or 70 per cent to the front, depending on grip. While the rear-wheel-drive BMW includes a clever limited-slip differential, it works its traction control harder – although it always intervenes smoothly. On the track, you can go for a dynamic setting that gives you more freedom, or turn the electronic safety nets off completely for tyre-smoking tail slides.

Worth considering

Porsche Panamera Turbo- The recently revised £107,903 Panamera Turbo has the badge kudos, power and performance to match the two cars in this test, thanks to its thumping 513bhp turbocharged V8 engine.

1st place - BMW M6

It's very expensive (especially compared to the mechanically identical M5), but the M6 Gran Coupé looks and feels special. With its agile rear-drive chassis, it’s rewarding to drive and offers pleasures beyond its staggering performance. It’s also more comfortable than the Audi. 

2nd place Audi RS7

With its powerful engine and quattro all-wheel drive, the RS7 offers supercar pace in a practical and stylish body. But while there’s lots of grip, the chassis disappoints, with an inert driving experience and an uncomfortable ride. And at this price you need more than just a great engine.