Within 8km of starting the twin-turbo V8 for the first time, the fire is muffled as the speed-limiter calls time just beyond 250km/h. And half of those kilometres were getting out of Munich airport and jumping onto the A92 autobahn. After the repressed driving culture of Australia, Germany is like heaven. Even at 250km/h, you’re often not the quickest thing on the autobahn so it pays to keep one eye on the mirrors and one eye on that Polish-registered truck in the slow lane. The jiggling headlights are closing in fast so I ease into a sizeable gap in the middle lane and continue to hold the throttle wide open. Just as the shape coalesces into a recognisable and legendary front end, the howling V10 becomes audible above the muted roar of the Audi’s V8. When the Porsche Carrera GT whumps past at close to Vmax, the S7 shimmers a little as the disturbed air washes over the bodywork. A mirror check and I’m back out into the fast lane hoping my co-pilot can snap off a shot but the Carrera GT has already opened up a 400 metre gap. A minute later it’s out of sight. Big respect. Even without the electronic interference of the speed limiter, the S7 wouldn’t have held the Carrera GT at bay for long – Audi engineers suggest it’d run to around 280km/h before aero drag would get the better of the power. The Audi’s twin turbo 4.0-litre V8 produces 309kW; a long way shy of the 450kW, 5.7-litre V10 in the Porsche. And while no one is going to confuse the S7 and its sober-suited S6 brother for a supercar, the S-twins are rapid cars. Audi claims 0-100km/h in 4.7 seconds; the S6 Avant matches this while the S6 sedan is a tenth quicker. Those numbers feel about right and there’s strong acceleration to about 200km/h before drag becomes a factor. Above 220km/h speed builds at a more leisurely pace. The same twin-turbo 4.0-litre V8 sees also duty in the S8 where it makes 388kW and 650Nm, and the Bentley Continental GT V8 (373kW/660Nm). This is likely to be the engine that will power the 2016 Lamborghini Urus super-SUV shown in concept form at Beijing. On the international launch of the S6 and S7 models there was some talk by various journalists that the S6 and S7 were underpowered to survive in the German power war. From the above numbers, it’s clear the engine is unstressed in this application but unlike some German rivals, the S7/S6 never feels overwhelmed by its engine. And power isn’t this engine’s only trick. Cylinder deactivation shuts down the intake and exhaust valves on cylinders 2, 3, 5 and 8, switching the V8 to a V4. The operating parameters of the system appear narrow; engine speed must be between 960-3500rpm, the seven-speed dual clutch transmission must be in third gear or higher and torque output must be between 25-35 percent of peak torque. The truth is, with such a wide spread of ratios, cylinder deactivation works up to at least 150km/h on a steady throttle. And its operation is seamless, which will be a shock to those of you who understand primary balance. Audi engineers have gone to incredible lengths to ensure you can’t pick when the system is operating. Active Noise Control (ANC) and dynamic engine mounts play a huge role in the technical subterfuge. Four microphones integrated into the headlining record the complete noise spectrum within the cabin, isolating and discarding music and conversation. When the cylinder deactivation shuts down half of the engine, a sensor at the crankshaft tells the microphones to generate a 3D ultrasonic pattern to disguise any vibrations from the unbalanced engine. The speakers work whether the audio system is on or off. It is a brilliant solution and there’s no way to tell when then engine is in V4 or V8 mode. You have to cheat and refer to the instrument display. Away from the autobahn and onto some twisty roads in the Alps, the S7, and especially the S6 which was fitted with the optional sports rear differential and dynamic steering, are more fun and agile than such a large luxury car has a right to be. Like most Audis, steering feel is hardly a strong suit, but the electromechanical steering is quick and there’s enormous traction from the quattro all-wheel drive set-up. Under normal circumstances, 60 percent of all torque is delivered to the rear wheels. When slip is detected, a maximum of 80 percent will be sent rearwards, or if it’s the rear wheels slipping, 70 percent of all torque will be shuffled forwards. The optional sport rear diff will vector torque across the back axle allowing 100 percent (of the 80 percent peak torque) to drive one rear wheel. Driving in both wet and dry conditions, the longitudinal grip is amazing. Lateral grip is a factor of tyre adhesion and the S6/S7 score strongly here as well. Standard tyres are 255/40 R19 (we tested Continental Contact Sports) for both models, though 255/35 R20s are optional and, in the case of the S7, 265/35 R21s. Despite the lack of sporty chassis options, the S7 was fitted with carbon ceramic rotors (which save 7.5kg in unsprung mass at each corner). Regardless of whether you option the carbons or stick with the cast-iron rotors, the front calipers are monster six-piston units. Neither the S6 nor S7 are track cars so save your cash and forget the carbons. Both models are fitted with adaptive sports air suspension. In the sportiest mode the suspension drops 10mm in the S7 and 20mm in the S6. While the car does sit flatter in this mode, the ride (especially that of the S6) deteriorates noticeably. The seven-speed dual clutch transmission delivers sporting shifts when the mood takes you, but most times is happy to blend into the background with almost imperceptible cog-swapping. It does a great job keeping the engine in its mid-range sweet spot. As we’ve come to expect from Audi, the interior of both models are works of art. The basic design is familiar from the A6 and A7 but with a sportier take. The sports seats with integrated headrests, quilted finish and deviated stitching are standard on the S7 and optional on the S6 models. Now for the bad news. Not all markets will get all three variants. Major European markets and the UK will take S6 sedan and Avant, and S7, but Australia has already ruled out S6 Avant. The USA and China are likely to follow suit and take only S6 sedan and S7. Only German pricing has been released at this stage where the S6 sedan costs 72,900 Euros, 75,250 Euros for the Avant and 79,900 Euros for the S7. The S6 sedan is expected to cost just shy of $200,000 when it goes on sale in Australia in October, while the S7 will crack the $200K barrier.