First drive: Audi lobs low-volume S6 and S7

AUDI’S sporty S6 sedan and slinky S7 fastback twins-under-the-skin have been launched in Australia in strictly limited numbers of 50 units apiece.

Powered by the same 309kW/550Nm twin-turbocharged V8 petrol engine, the duo will sit atop Audi’s ‘S’ performance range as the larger and costlier S8 limousine sold overseas is deemed unsuitable for this market.

The fourth-generation S6 sedan is based on the A6 launched this time last year and is priced at $168,900 plus on-road costs, putting it well above the $121,000 3.0 TFSI A6 flagship but more than $30,000 below its predecessor, which was powered by a more powerful Lamborghini V10.

The first-generation S7 coupe/hatch is priced $11,000 higher at $179,900, but is fundamentally the same as the S6 sedan underneath its sleeker bodyshell, with the notable exception of accommodating four rather than five occupants.

Neither S model is pitched as an out-and-out sportscar – that tag is reserved for Audi’s more hardcore RS models – but rather as a quicker-than-average grand tourer with sporting pretensions.

The S6 is therefore a natural rival not for the similarly sized BMW M5 – or Mercedes-Benz E63 AMG – but rather the less-extreme 300kW/600Nm 5 Series 550i ($179,400).

The S7’s most obvious competitor is the 300kW/600Nm Benz CLS 500 ($210,800)The twin-turbo V8 engine in both models is similar to that in the Continental GT from sister company Bentley, and sends power to all four wheels via Audi’s 40:60 front/rear quattro all-wheel-drive system and seven-speed dual-clutch S tronic transmission.

The 1970kg S6 accelerated from 0-100km/h in a claimed 4.6 seconds, while the 50kg heavier 2020kg S7 takes an extra tenth, and both have the same electronically limited 250km/h top speed.

With GM-style cylinder-deactivation, which switches off four of the eight cylinders when cruising, both models return a respectable 9.6 litres per 100km on the combined fuel economy cycle.

To counter NVH issues when running on four cylinders, Audi fitted active engine mounts and active noise control, the latter working like noise-cancelling headphones by sending a countering note into the cabin via the speakers.

Beneath the different bodies sits the same lightweight partial-aluminium underpinnings that places the engine block further back from the front to improve balance.

Both models feature the same fuel-saving electro-mechanical powered steering, adaptive air suspension that lowers the S7 by 10mm and the S6 by 20mm at speed, and 20-inch five-spoke alloy wheels (though the S7’s wheels and Pirelli P Zero tyres are slightly wider).

The suspension can be altered via the Audi Drive Select dial, which also adjusts the steering, gearshift and throttle to be either more soft and relaxed or hard and sporty.

Equipment levels are almost identical, including digital TV reception, electric boot open and closing function, head-up display, LED headlights with high-beam assist, electric glass sunroof, dual-zone climate-control, keyless entry and start, Bose 14-speaker iPod/AUX/MP3 system with Bluetooth, satellite-navigation and S Sport front Valcona leather seats (the S7 also gets S-Sport rear seats).

Audi charges a steep $6300 for the option of adaptive cruise control, autonomous braking, active lane assist, blind-spot monitoring and park assist.

Standard safety equipment for the five-star Euro NCAP-rated models includes eight airbags, stability and traction control, ABS with EBD and brake assist, tyre-pressure monitoring, parking sensors and a reversing camera.

2012 Audi S6 and S7 pricing*

S6	$168,900
S7	$179,900

*Plus on-road costs