An all-new, turbocharged V8 is threatening to put the V10-powered Audi R8 supercar into the shade by turning the German brand's upcoming RS6 into the fastest road car ever built by the company.
The new Audi A6's dust covers haven't hit the ground yet, but sources are already insisting the German brand is preparing a V8 onslaught - and one that might even see the new car cracking sub-four-second zero-to-100kph sprints.
Wary of BMW's upcoming turbocharged V8-powered M5, Audi has ditched the old RS6's twin-turbo, Lamborghini-sourced V10 for an all-new turbocharged V8 engine family of its own, sources insist.
Developed in conjunction with its British brand, Bentley, two versions of the 4.0L, turbocharged V8 will sit beneath Audi engine bays, including a crunching 555hp version for the RS6. It is believed Audi has developed a single-turbo version of the engine for the S6, S7 and S8 along with a twin-turbo version for even higher performance demands.
While it will also be fitted to the Bentley Continental series to provide an entry-level motor, the more-upmarket brand will retain its own larger, 6.7L turbo V8 for the Mulsanne.
The new engine will also find its way inside the A8 and the A7 and will boast direct-injection and a 90- degree vee angle, but will retain Audi's traditional bore spacings and will still be built in Gyor, Hungary, before being shipped across to Quattro GmbH.
Inside the lighter, stiffer A6 chassis, the all-alloy, twin-turbo version should propel the RS6 into the low four-second bracket for the sprint to 100kph (the 295hp, 3.0L, supercharged V6 version already manages it in 5.5).
The raucous, old, twin-turbo V10 RS6 sedan had 571hp of power and could run to 100kph in 4.5 seconds, but that's just a tenth quicker than the hot-hatch RS3 can manage today.
While the Quattro boss, Stephan Reil, recently insisted the monstrous twin-turbo V10 has a future inside RS Audis, the output differences between it and the twin-turbo V8 seem so negligible that its retention would make little sense, either economically or in terms of performance.
Sources instead insist the new engine will mate inside the RS6 to a stronger version of the A6's current double-clutch, seven-speed gearbox and will use the crown-wheel centre diff technology that has proven so successful on the RS5. The engine's torque is said to be in the 620Nm region, or close to the old V10's 650Nm output, though it's a lighter engine in a lighter car.
While it will be slower, Audi will sell more of the single-turbo versions of the engine when it fits it to S versions of both the A6 and the five-door A7. The high-tech, 4.0L motor will produce at least 422hp and will eventually find its way inside the A8's engine bay as well.
Both V8s will continue the handling improvements that the new A6 benefits from, with the RS6, in particular, losing a significant amount of weight from on top its front axle.