IN THIS FEATURE An air of restraint Brisk yet relentless A glint in its eye Fuel consumption could be a problem

It may be muted but the engine is a bit of a technical wonder. The advanced FSI direct injection 5.2- long-stroke litre V10 engine is fitted with continuously adjustable camshafts and twin engine management systems to produce 435bhp at 6,800rpm and 398lb-ft of torque at 3,000rpm. Flex that muscle and the S6 will hit 62mph in a mere 5.3seconds and not stop until it's electronically tagged at 155mph. That's Porsche 911 quick.

The introduction of FSI direct injection - a first on a V10 engine for Audi - and an ultra-high 12.5:1 compression ration makes for a hugely efficient combustion process - and a correspondingly deep torque reservoir. At 2,250-5,850rpm a full 90% of the 398lb-ft of peak torque is available. The result is a seemingly inexhaustible flow of acceleration to slingshot the car out of tight corners and simply annihilate slower traffic when overtaking.

You'll need to check the speedo to realise how relentless acceleration is

It sounds mean-spirited to describe the S6 as merely brisk, but so smooth and velvety is the power delivery that the S6 never feels cor blimey quick. You know you're moving at a fair old lick, but you'll need to glance down to the teardrop speedometer to realise just how quickly and relentlessly the S6 accumulates speed.

The engine's urbane demeanour is perfectly matched by the clean-shifting Tiptronic gearbox, which slips quickly and unobtrusively between its six gears. The gear ratios themselves are shorter and the change times quicker, so tapping the chrome gearshift paddles results in instant gear changes.