Audi S6 VS Audi S4

The S6 sedan has no right being this good in a straight line and around corners…

Much of its success is owed to the 2.9-litre twin-turbo V6, which is now one of my favourite engines being built today. Simply put, it absolutely hammers.

Punch the accelerator from a standing start and it doesn’t take long for 600Nm to be on tap all the way through, and just a little bit beyond, the mid-range.

Occupants are firmly pressed into their seats as the S6 sedan sprints towards the horizon with vigour. Soon enough, 331kW arrives and hangs around until just prior to the redline.

Needless to say, this acceleration is addictive, and the EPC deserves some of the credit, as it effectively mitigates any dreaded turbo lag and ensures the engine is always seemingly on boost.

But we also need to acknowledge the eight-speed torque-converter automatic, which is a real beauty. Gear changes are nice and smooth, which is great, but what’s even better is their relative quickness – dual-clutch transmissions be damned!

Of course, extra performance can be extracted by switching between the engine and transmissions’ settings but, rest assured, they both stand up, no matter what.

However, we’d suggest spending time in the former’s most aggressive setting, as it unleashes the sports exhaust system, which sounds unreal.

Upshift with intent and you’re met with a booming ‘brap’. Downshifts and the overrun will even gift you a series of pops. In fact, the S6 sedan soundtrack sounds strangely similar to that of the five-cylinder RS3, and we have absolutely no problem with that.

Better yet, the S6 sedan has an appetite for corners, with its neutral handling a standout, partly thanks to its hard-working rear-biased quattro all-wheel-drive system, which works in tandem with all the other electronics to ensure there is plenty of grip at any given time.

This controlled driving pleasure is enhanced by the electric power steering on hand, which has a variable ratio. At low speed, it’s nice and light, but those after more heft can always switch to another one of its settings, which become progressively heavier… arguably too heavy.

Feedback through the wheel is also good, while the steering itself is pretty direct, lending itself to sporty driving, which, of course, is half of the S6 sedan’s mantra.

Coming into corners, braking performance is solid, thanks to the massive 400mm front and 350mm rear discs with red callipers, so the driver is brimming with confidence at every turn, even though there’s an unladen weight (with 75kg driver and luggage) of 1985kg to manage.

But let’s not forget the S6 is an executive sedan, so it has to ride like one. Thankfully, it does. The independent five-link suspension has air springs and adaptive dampers, which serve up comfort in spades, especially at high speed.

Its firm tune does come into frame when travelling on unsealed or uneven roads, with this exacerbated by the large 21-inch alloy wheels, which have a penchant for catching sharp edges.

The S4 is terrific fun. It's that simple. The new engine is an absolute belter, with all 500Nm of torque available at just 1370rpm. Lag is almost indistinguishable as the turbo spools up and rockets you along to 100kmh in under five seconds, that huge half-ton of torque sweeping you down the road.

With dynamic mode switched on, the car muscles up with firmer suspension and a slightly growlier exhaust. The steering really weights up, too, which takes a little getting used to after the lighter, friendlier setting in Comfort mode - thankfully you can set up an individual mode to dial the assistance back in while everything else is set up for go-fast.

The key to the fun is the rear-biased quattro system - while it's never going to match the purity of BMW's rear-wheel drive 340i, what you lose in steering feel and ultimate adjustability, you gain in off-the-line and mid-corner grip its German rivals could only dream of.

Going fast in an S4 is easy, leaving you to concentrate a little more on your line and gear selection, listening to the distant bark of the engine and the occasional turbo whistle. All of this is purely down to driving taste, of course but the point is, the S4 offers something a little different to the other two. 

For most of the time the S4 defies its 1700kg-plus weight but there is the occasional hesitancy when changing direction through a challenging set of bends, as though the front tyres (245s all around, if you're interested) want to scrub and the quattro system makes a quick adjustment to stop it happening. You don't feel that's what's happening, of course - Audi Sport is better than that - but it's part and parcel of all-wheel drive. It takes a lot to find understeer and for most people, that just won't ever happen.

Further confidence comes from the terrific brakes - 350mm up front and 330mm at the rear, the big forward rotors are gripped by six-pot fixed calipers. Performance is epic and in hard, fast driving they stood up to a fair amount of punishment without fading.

The ride is excellent in all modes, which is quite an achievement given the fat rubber and big wheels, although big bumps at speed make a huge metallic thunk without actually upsetting progress. The eight-speed ZF is brilliant as always and unless you're really motoring, you don't even need its sport mode, which brings impressively fast and positive shifts.

The best thing is, if you don't look in the rear vision mirror, you can't really tell if you're driving sedan or Avant. That might be because it's quite absorbing on a launch drive, but I couldn't split the driving experience between the two.

The only black marks I could easily identify on the S4 is tyre noise on some surfaces and perhaps the steering could be a little more lively like its competitors.