AUDI’S RS6 is something of a swansong for the current A6 large sedan series. Its stupendous on-road capabilities rate it in revered territory, up there with BMW M5 and Mercedes E55 AMG – an achievement the A6 itself has never quite managed among its BMW and Mercedes peers. With Porsche 911 Turbo-like acceleration, the grip of constant all-wheel drive and a classy, subtle but aggressive on-road stance, RS6 could lay claim to being one of the great all-time high-performance luxury sedans. And although its price almost approaches three times that of a base-level A6, it’s entirely competitive in its category and a good investment in outright performance.