Audi S7 Sportback vs. Porsche Panamera GTS: V8 turbo vs. V8 naturally aspirated engine in the comparison test

For Audi's sports saloons, turbo was at one time a bringer of relief, for the Porsche Panamera GTS it is the sword of Damocles, that will one day catch up with it. A battle of the concepts, but one that is not decided by the engines.

No question, we have grossly underestimated the turbo virus. In the beginning we found it cute, celebrated it as an effective anti-depressant against boring basic-level petrol engines and occasionally allowed ourselves – if we are honest – to enjoy having our senses clouded by its boost pressure. Only now, as it gradually infests our sanctuaries, are we really becoming aware of the extent of the epidemic.

Porsche Panamera GTS with a 4.8-litre V8

Porsche is a particularly tragic case. For decades they bred turbochargers there in quarantine, isolated them in high-performance top models – and now idly observe how they are gradually spreading across the model family, disguised as a cure-all remedy. With devastating consequences.

The two SUV series are already turbo-infested across the board; presumably the Boxster, Cayman, Carrera and GT3 will only be able to resist until the next model upgrade; and in the Porsche Panamera it has already wiped out all naturally aspirated engines when the model underwent a facelift one and a half years ago – all with the exception of the 4.8-litre engine in the GTS, which as if by a miracle survived the massacre unharmed.

Why cannot actually be explained. Perhaps because they want to break the unavoidable trend reversal to customers gently? Or perhaps because on the executive floor at Porsche they do not simply want to rule by the VW handbook, but also with their hearts? One way or another, the glimmer of hope will presumably be shortlived: it still has two, maybe three years, the Porsche Panamera GTS, and then they will place it in a museum – with new tyres, a full body treatment, a red rope surrounding it and an enamel board as a gravestone.

Audi S7 Sportback produces 444 HP

And the significance of the Porsche Panamera GTS is greater than one might think. At Porsche it might currently be one of a decreasing number of naturally aspirated models, but it is actually the last in its league. Take a moment to quietly think it through: Audi, BMW, Mercedes, Jaguar – nothing. Ultimately: between the old-school V6 of an Infiniti and the V12 higher nobility, à la Aston Martin Rapide S and Ferrari FF, there are no more like it.

But parting ways is not always painful. Or do you still take time to remember the V10 in the deceased Audi S6? That 5.2-litre hunk, which could conceal its Lamborghini ancestry as well as the alleged 429 HP. Around three years ago, after just a short period in office, it was thrown out on its ear and replaced with a biturbo, which, had they flowed, would have dried the tears in an instant – even in spite of the decrease in power.

Since then, the four-litre has taken care of everything to do with high power that comes up within the group. It plays the part of the 552 HP beast in the RS models, as well as the tenderly melting V8 in the A8 and has evven made it over to the UK in various Bentley Continentals. In the Audi S7 Sportback, which on account of its flowing back end is a closer match to the Porsche Panamera GTS than the structurally identical S6, it initially produces 414 HP.

A big difference in Hockenheim

As a result of the model upgrade, the Audi S7 Sportback has now been boosted with an additional 29 HP, although this has as little effect on the basic overall sensation as the 9 HP that Porsche recently credited to the Panamera GTS. This means: although both have actually become a touch faster as promised, owners of previous generations have no need to fear that they will be technically surpassed – or worse yet: overtaken.

Much more noteworthy than the question as to the extent to which the two cars break away from their predecessors is the question as to how two cars of this type, which are,, nominally speaking, so similar can set themselves apart from one another. 10 HP, 30 Nm and not even 40 kilograms separate the Audi S7 Sportback and Porsche Panamera GTS, and just six tenths in the sprint to 200 km/h – although in the end the difference is a huge 3.1 seconds in Hockenheim.

In the comparison test, the Porsche Panamera GTS instantly seems more focused: rev counter centrally positioned, steeply angled Alcantara steering wheel with implied central marking and ergonomic seats that suck you right into the action. When starting off, the V8 of the Porsche Panamera GTS blows out through the sports exhaust as if bunged up with the cold, before it either gently nestles against one of its two couplings or pummels on the drive chain at just under 6,000 rpm via the Launch Control. 17.2 seconds to get to 200, a max. speed of 288, but the destination is actually the journey.

The Audi S7 with a hefty maximum torque

Up to 4,000 rpm you mill along – well we say that – determinedly, however in excess of this, the short-stroke engine fires furiously up the speedometer, turns, thrusts, trumpets and clicks, and not just because the dual clutch transmission gives it an extra kick up the backside when gearing up. Granted, you notice that there are almost two tonnes hanging on the rev bands; granted you are continually changing gear if you really want to make progress; and granted you not only experience the maximum torque earlier in the Audi S7 Sportback, but also more intensely. However, there is no other four-door car that – its obese anatomy hidden – really conveys the illusion of being a sports car so deceptively.

In the Audi S7 Sportback, on the other hand, its sporty side is only expressed subliminally – if at all. Viewed separately, the S7 could be an athlete, however, in relation to the Porsche Panamera GTS it feels like the bubbly Jacuzzi after the workout. This has its appeal, no question, but it is not truly captivating. Also on account of the biturbo concept.

We can explain it like this: Instead of pulling itself together, thrashing, biting and sacrificing itself to the limiter gear for gear like the Porsche, the Audi V8 simply takes a short run-up, and skips a few hundred rpm so as to let itself be carried away by the gust of wind provided by the boost pressure. In theory, this gust of wind blows at full strength over a range of 4,300 rpm. With long strokes, playfully, accompanied by storm-like rumbling from the exhaust, but – a compliment – respectably enough that you can still detect the firing strokes of the combustion engine from beneath the turbo hurricane.

The Porsche Panamera GTS outsmarts physics

Generally, the Audi S7 Sportback and Porsche Panamera GTS find the right balance with regard to their engines: for in contrast to their closest siblings within the model range, they can also be enjoyed in everyday life. Certainly on the motorway, but also along your personal favourite route: via the back roads, through all the little towns. There, with the RS7 or Panamera Turbo, you can breeze along between cornfields at a rate of knots, at two hundred plus, but in the Audi S7 Sportback and Porsche Panamera GTS you can drive to the limit without risking being thrown in prison.

Limitation: even though the engines of the large vehicles are really well hidden by the bodywork, in the end the two-metre width is still two metres, and with a tractor on the left, boundary posts, three figures on the speedo – you know where we're heading with this

However, on the racetrack the significance of these kinds of external factors on physics is reduced. And regarding physics, we are often glad to report that it cannot be outsmarted. Well, that said, with the Panamera GTS Porsche has managed it. Total nonsense the scientist will now say. Our response: come, drive, believe!

The Audi S7 Sportback holds its head high

In the comparison test it continually lies in wait, even when strolling along, immediately engaging the lower gears as soon as you brake a little more heavily and continually provides you with accurate information as to what is happening beneath the Michelin tyres, via the steering and chassis. This may just be fun on country roads, but in Hockenheim it is deadly serious. How it steers, throws itself into corners, anchors the car body to the horizontals, supports itself on its radical Michelins and drives over all four wheels with incredible neutrality from the corner – sorry, but this is not of this world.

Or to express it another way: the performance of the Porsche Panamera GTS cannot be grasped, but it can be explained. Firstly with the general Porsche philosophy whereby cars are built according to sports car standards, which are actually by no means standard. And secondly, of course, with complex technical gimmicks such as active stabilisers, intelligent pneumatic suspension and torque vectors at the rear axle, whose interplay enables cornering speeds beyond (exclamation mark) those of a current 911 GT3 (three exclamation marks). Put clearly: in the GTS version, the Panamera is closer to any 911 than the Audi S7 Sportback, which in this respect can only comfort itself in that fact that it has gone out with its head held high.

The completely decoupled dynamic steering with its muddy central position and the swaying body movements in the slalom at first have you fearing the worst. On the lap, however, its air suspension suddenly kicks in, flicks it into the corner without understeer and when exiting the corner even – thanks to the transverse-locking rear axle back-heavy all-wheel drive – carves out some fully fledged drifts. The fact that, in so doing, the Audi S7 Sportback doesn't come anywhere close to the Porsche is down to several reasons: the more conservative tyre combination, the lack of roll compensation or the more tame transmission for example; the fact that it also loses the surreptitious sympathy points is down to just one thing: the unrelenting naturally aspirated engine in the Porsche, which – as absurd as it may be amongst the rowdy turbos – is still the most normal thing in the entire car.

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11 March 2015
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