This is an area that the A6’s rivals struggle with, particularly with their equivalent four-cylinder diesel engines. Audi has managed to abolish the diesel clatter from its four-cylinder 2.0-litre engine, though, even at high revs. You feel precious little vibration, too.
The 3.0-litre diesels are also smooth, but there’s more of a background grumble at idle and when pushed beyond 3000rpm. The noise isn’t intrusive, though, and the BiTDI sounds genuinely sporty. You’ll also hear the engine in the S6, but its V8 burble is exactly the sort of noise you’ll want to hear in a performance saloon.
Otherwise, there’s some wind noise on the motorway and a little road noise on coarse surfaces, especially on models with larger wheels, but, on the whole the A6 is a superbly refined car. In fact, it’s one of the quietest executive cars money can buy.
Most versions are fitted with a seven-speed S tronic automatic gearbox, which can be a little jerky at manoeuvring speeds, but is otherwise slick. The BiTDI gets an eight-speed automatic ’box, which is smooth at all speeds.