What's astonishing is the way it shrugs off its weight and turns in so quickly, partly due to the clever 4x4 system, partly the active engine mounts and also a basically sound suspension set up. It certainly lays down a gauntlet for the super saloons on the way including Jaguar's XF-R, BMW's M5 and Porsche's Panamera Turbo.

Out on the road the AMG feels more antiseptic. Even driving hard you are a bit of a passenger and there's little information about what it's doing or how it is doing it. There's a palpable sense of exhilaration and fun, though even if you never approach the limits of grip.

In fact its best trick is when you aren't driving fast at all. Merely drafting along with normal traffic, the engine barely turning over with all the dynamics set to cruise. There it feels strangely like the great American muscle cars; soft, but super powerful, ready to battle for pink slips in any impromptu drag race. Ahead the traffic gently parts and the big V8 burbles past commanding respect and awe in equal measure.

I've driven some great cars this year, but none of them as hilarious as this. Mercedes-AMG has made its most memorable monster yet.