It may be difficult to predict exactly how much appetite the UK’s sports saloon faithful currently has for the fast, diesel-engined four-door.
Some manufacturers clearly think it’s so meagre as to justify the early removal of derivatives and the cancellation of development programmes; some, but not all. And perhaps it’s appropriate that, having had such a significant hand in the scandal that did so much damage to the reputation of diesel engine technology back in 2015, Audi should now be the company doing what it can to restore that reputation.
As the Ingolstadt firm announced earlier in 2019, all future S-badged go-faster Audi models in Europe, bar one or two, are now to come with diesel engines intended to be equally big on torque and accessible for pace as they are fuel efficient and long striding in real-world use. Some, like the SQ-tagged performance SUVs, already were diesels, of course; but for Audi’s longer-lived and more celebrated quattro-driven sports saloons – one of which, in its latest guise, is this week’s test subject – that’s a major development.
So what will diesel power mean, exactly, for this heavily facelifted sixth-generation S4 aside from the addition of a TDI naming suffix?
The best way to sum it up in headline terms may be to record that it has as much torque as the maddest Mercedes-AMG C63 super-saloon – but it is also rated for better than 40mpg on the latest WLTP combined fuel economy lab tests, offers twice as many driven wheels as the Merc and yet can be bought for two-thirds of the price.