Audi RS6 VS Audi S4

As you might have guessed from its impressive engine and performance equipment, the RS6 is a certified weapon on road and track.

On the road you can expect a quiet, refined cabin, superbly balanced steering for low and high speeds and a gentle ride quality courtesy of the pricey air set-up.

It’s as noisy or as quiet as you want it to be, with the cylinder deactivation toning things down at low speeds, and the engine roaring to life under heavy acceleration, or when the 'Dynamic' drive mode is selected.

It can at times be alarming how much the RS6 leaps to life, as it feels so cushy in a city, its width and cabin giving the feel of a luxury car rather than a performance one.

Make no mistake, though, the RS6 is properly quick, and when you give it a kick, it’s the roaring, aggressive machine the spec sheet suggests.

The best place for this? The track, of course. The big V8 and the capability of the all-wheel drive system are truly best explored at velocities impossible to legally achieve on the road.

Once you get past the bark and snarl of this wagon’s eight-cylinders at full force, and the lightning-fast shifts of its eight-speed automatic, you’ll have a moment to appreciate the way it simply holds to the tarmac when you tilt it into the corners, providing a balance when loaded up which only air suspension can provide.

The steering is awesome, communicating the texture of the road nicely to the driver, and requiring just the right amount of force to keep the car pointing where it needs to go.

The grip level is astounding with the huge tyres and the four-wheel steer system lets this hefty wagon take corners at a tighter angle than your brain initially allows.

Thankfully, the four-wheel steer system isn’t weird, either. While it can have a strange effect on some cars, in the RS6 it only bends your mind slightly when you tip it into a hairpin. Otherwise it feels pretty normal.

When everything is warmed up, it can let its guard down slightly and allows the driver to eke out a slide at the rear here and there for extra fun-factor

Jeez. What a machine. I guess this is what a quarter of a million dollars buys. A car that can do it all. Take the kids to the school in comfort and tear it up on the track like few other passenger cars on the same day.

There’s a caveat, though. A small one which looks like it will turn into a big one for cars like this in the near future.

I had the opportunity to drive the RS e-tron GT around the same circuit and it was better. Much better.

It was faster, more accurate, more composed. It was so effortless, I didn’t realise exactly how much quicker than the RS6 it was until I drove them back-to-back.

It’s a good sign for the future, but also a reminder a V8 like this isn’t the performance pinnacle it once was.

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.