Audi often faces accusations of playing it a little too safe with the dynamic set-up of its cars but a bit of greasiness under tyre revealed an unexpected - and welcome - hint of playfulness in the TT. On a day like that a Boxster driver would have struggled to keep up, the TT S Roadster deploying trademark four-wheel drive traction and security with a tasty garnish of of adjustability in the form of subtle four-wheel drifts under power. Can similar conditions put the S5 in a favourable light against the dominant rear-driven rival?
We're talking of course about BMW's 4 Series. Over the years the faster versions of this (and its 3 Series coupe predecessor) have traditionally over-delivered, to the point you might even consider the value of stretching to the proper M versions. Audi has never quite captured the hearts or minds of keener drivers with the A5 or its faster versions, even when there was a glorious sounding V8 under the bonnet. With this all-new A5, especially with the S5, Audi has an opportunity to start afresh and really take the challenge to BMW.
Star of the show must be the S5's new engine, rumoured to have been jointly developed with Porsche.
Mercifully, we're not talking about the controversial flat-four turbo but the new 60-degree, 3.0-litre V6 that, thanks to its modular nature, will one day soon gain extra cylinders to become the 4.0-litre twin-turbo V8 at the heart of the next Panamera.
It's a clever piece of kit. 14kg lighter than the previous supercharged 3.0, despite sharing the same swept capacity, the new V6 turbo has been lavished with attention and has lots of geeky detail to enjoy. This includes combined direct and indirect fuel injection and a single twinscroll turbo contained within the vee of the cylinder banks - as usual in these installations the boast is of the shorter plumbing improving response while the engineering involved has required some genuine artistry, at least according to one enthusiastic engineer.
Power and torque prove what a serious unit it is, with the 3.0-litre generating 354hp and 369 lb ft. Perhaps most impressively, the latter is churned out from just 1,370rpm with a steady block of torque stretching all the way to 4,500rpm.
Channelling the power to all four wheels you might expect Audi to have rolled out a version of its seven-speed dual-clutch S Tronic transmission. But it hasn't. Instead, the V6 turbo comes with ZF's all-conquering eight-speed automatic. We couldn't get to the bottom of whether the new engine's higher torque ruled out using a DSG but, even without launch control, the new engine and transmission combo delivers a stunning 4.7-second sprint to 62mph - two tenths faster than the old car.
Those figures beat the BMW by three tenths and matches the fast Mercedes-AMG C43 AMG, the latter also four-wheel drive of course. Of course, it's not just sheer power helping the new S5 whip the 440i in a straight line - despite being longer (29mm) and wider (16mm) than the old model the S5 weighs in 75kg less than the old model thanks to its new platform. Even with an extra set of driven wheel the S5 is 15kg lighter than the rear-wheel drive BMW 440i, there being no xDrive four-wheel drive version of this model. Like other Audi models, the Quattro comes with a locking centre diff that can run 60 per cent of torque rearwards. In extreme conditions that figure climbs to 85 per cent.
Alternatively, to help drag you out of slow corners, the same system can shuffle 70 per cent torque forwards. On the S5 an optional Sport Differential provides additional torque-vectoring on the rear axle to reduce understeer. So far, so good. Lighter, more powerful, faster with a proper rear-biased all-wheel drive system. What's not to like?
Well... Q-car stealthiness has always been an S Audi hallmark but among the launch fleet of 2.0 TDIs the Daytona Grey S5s were completely lost. You get the trademark silver wing mirrors of course, likewise bigger front air intakes and quad exhausts. But it's possibly a little too underplayed, perhaps so as not to tread too hard on the toes of the forthcoming RS model.
At this point I should mutter something about 'soft-touch plastics' because, apparently, car hacks are obsessed by the plumpness of dash coverings. Suffice to say, the S5's are very plump. Moving on, Audi's 12.3-inch virtual cockpit remains impressive, although things can get very confusing when you display sat nav instructions on the dash, head-up display and the little centrally-mounted tablet since the information offered differs on each screen. Pray for me.
By now, it might feel as though I'm stalling on sharing the driving experience. I am, because back on those wet roads the S5 is a confusing car to get your head round. Great traction dominates the experience, even on the roads where small rivers threaten to wash us and the road away. In many ways it was the same for the TT S back in Majorca. But where the little roadster thrilled the S5 leaves you cold.
Pace isn't the problem, but the new eight-speed auto is. In its fastest Dynamic mode it's super quick to react and there are no complaints over how quickly it shifts up and down the box. Where the package stumbles is the quality of the shift, with surprising jerkiness not normally associated with this particular transmission. It almost feels as though some of the old car's DSG's 'character' has been engineered into the new car's software maps.
Next gripe will sound a little churlish. The engine is mighty but with so much torque so early in the rev range its urge feels unremitting. An odd complaint perhaps and it is, of course, hugely flexible and tractable as a result. But the soulless drone it emits can't even be enlivened with a few muffled pops on overrun.
This character continues in the way it drives. First in the dock is the steering. All our cars came with Audi's Dynamic Steering and you can guess what's coming next. In the S5 the system is, at best, inconsistent. At worst a fundamental barrier to enjoying and exploiting the S5's handling.
Wind on some lock and immediately, off-centre, it feels unnervingly fast. On the treacherous roads it's far too easy to unbalance the car on turn-in. Worse still, wind more lock on and it feels like the steering response slows. Switching to comfort helps, but then the throttle and gearbox response make it feel like you've left the handbrake on. Switching to Individual mode is your only option to lock the steering in Comfort while dialling everything else back up to maximum attack.
Do that and feel is still lacking. Grip too, surprisingly. Even with relatively generous 255/35 R19 rubber and a 14mm longer wheelbase, the S5 struggles to be anything other than either inert or understeery. To be fair, at times the road surface feels like ice, but even in these conditions you would hope coming off the throttle would alter your line, help the front tyres regain some composure, add some balance, god forbid, even allow the S5's tail to arc wide a few degrees. It seems to do little.
The key, of course, is to be more aggressive, turn in on the brakes at all times and then feed the throttle in as soon as you can but, even then, the S5 is unwilling to give anything back. Perhaps dry roads would unlock the playfulness we're looking for. But from our first impressions, where the old supercharged S5 was edging towards something more akin to a sports car, the new S5 seems more intent on living the junior grand tourer dream.
The ride, for example, is decent, even in its firmest damper setting, That must be music to the ears for many who will buy a S5, and apparently one in four A5 buyers will. But it's a shame for those of us who want something a little more inspirational, perhaps to cheer you up after a long day at work. A car that's worth driving for the sake of driving, if you will.
The Audi S5 doesn't feel like it's that car. Instead of flattering the S5's abilities as you might have expected to the lousy weather did the completely opposite. It exposed its failings.
Engine: 2,995cc turbocharged V6
Transmission: 8-speed automatic, four-wheel drive
Power (hp): 354@5,400-6,400rpm
Torque (lb ft): 369@1,370-4,500rpm
Top speed: 155mph
MPG: 38.7mpg (NEDC combined)