Audi S6 TDI Review: Fast And Capable, But Where's The Excitement?

A switch to diesel power for the S6 isn't without its successes, but the results leave us a little cold

The new S4 going diesel isn’t something that’s bothered me all that much. It’d already gone from being powered by a heroic N/A V8 to a supercharged V6 and then an utterly fully turbocharged V6, the ditching of which seemed like no loss.

But for the S6, its fall from internally combusted grace has been more dramatic. It wasn’t all that long ago that Audi was fitting these with 5.0-litre atmospheric V10s, around the time of other absurdities like the V12 TDI Q7. The S6 lost a couple of cylinders for the C7 generation, but still, a 4.0-litre twin-turbo V8 is not to be sniffed at.

Audi - Audi S6 TDI Review: Fast And Capable, But Where's The Excitement? - Features

To go from there to a V6 diesel (some markets get a V6 petrol), seems like one hell of a downgrade. Particularly when power is now down by around 70bhp to 342, but with the torque rated at 516lb ft we at least have an increase of 100lb ft to play with here.

It does feel quick, too. To go with the V6 TDI engine, it has a 48-volt mild hybrid system which powers an electric compressor capable of spinning at up to 70,000rpm. It doesn’t need to wait for exhaust gasses to spool up, meaning it’s a highly effective tool to vanquish lag, something which - as a consequence - the S6 has precious little of.

Audi - Audi S6 TDI Review: Fast And Capable, But Where's The Excitement? - Features

The S6 will happily fire itself down a road at a tremendous rate, making you forget all about the fact its 5.1-second 0-62mph time makes it half a second slower than the old V8 version. It doesn’t even sound that bad. With the dynamic mode of ‘our’ S6 longtermer turned on, there’s a synthetic growl added to the mix (via a vibrating element in the exhaust), which sounds like heresy, but it does work reasonably well. Just don’t look too closely at the tailpipes themselves, which are so blatantly fake it’s actually offensive.

The S6 isn’t just a straight-line weapon, either. More than a lot of cars I’ve tried with rear-wheel steering, you can really feel the system working here. There’s a noticeable pivoting feeling when you’re seemingly pushing your luck in tight corners, ensuring the S6 doesn’t feel anything like the big, circa-two-tonne car it is. The optional air suspension fitted here keeps the body nicely level, too.

Audi - Audi S6 TDI Review: Fast And Capable, But Where's The Excitement? - Features

It’s a horribly greasy day today, but that doesn’t bother the all-wheel drive system one bit. Traction is provided in a supply that seems endless, and that characteristic understeer that fast Audis used to be known for is conspicuously absent.

On a road like this in these conditions, few cars are going to be as quick and confidence-inspiring. From the beefy mid-range torque to the resolute traction, the TDI S6 is an extraordinarily effective way of going from point to point. But it’s not all good news.

Audi - Audi S6 TDI Review: Fast And Capable, But Where's The Excitement? - Features

The gearbox, while speedy enough if you’re using the overly-plasticy paddles, isn’t slick enough when under its own control. And like so many V6 TDI Audi models with this transmission, it seems to take an age for the S6 to set off from a standstill after you put your foot down. That gap you thought was sufficient for pulling onto a roundabout? Best double that when driving one of these.

The interior feels upscale and more modern than the stuff BMW is churning out at the moment, but ditching physical climate controls and dumping them in a touchscreen - while also binning the old rotary controller - feels like a distracting backwards step.

Audi - Audi S6 TDI Review: Fast And Capable, But Where's The Excitement? - Features

The steering is too light and doesn’t give any real hint of feedback, but a more fundamental issue is just that the S6, while incredibly capable, simply isn’t that exciting. A more interesting engine could have elevated it above its lesser A6 brethren nicely, but instead, the S6 leaves you wondering if the much cheaper and not much slower 50 TDI is a better bet.

Granted, the same can be said of the S4 vs the A4 50, but the more junior S car just about justifies its existence. When you’re talking about an S6 which costs £77,980 with options and has a recent history of awesome powerplants, expectations are higher.