Audi RS6 (2013) review

Of course, adding lightness is good for efficiency, and the new RS6 is a decent chunk more fuel-efficient than the old version - up to 30 per cent. Part of that is down to clever aircon and thermal management, but there's also COD (Cylinder On Demand) tech in the engine, which we've seen before on various cars. This simply shuts down half the cylinders when running a light throttle. In the case of the RS6, if you're using under 3,500rpm on a constant load, then the car drops cylinders 2, 3, 5 and 8 out of service. Doing so generally reduces fuel consumption by about five per cent on the usual combined cycle, or as much as 12 per cent at a steady 62mph cruise. Which isn't to be sniffed at, especially as a twin-turbo V8 isn't likely to be particularly drink-shy if you decide to boot it.