You might remember the RS6 before this one had a detuned 5.2-litre Lamborghini V10 crammed into the nose, boosted and torqued-up for super-wagon duty by twin turbos. It was the undisputed fast estate king, thanks to 572bhp. And when Audi replaced it, the new RS6 boasted fewer cylinders. And less power. Could der fasczinating German power wars really be over?