This is a Bentley with a diesel engine. And that was the first time you will ever have read those words.
Until now, Bentley has never made an oil-burner. But here’s a Bentayga with the VW Group’s 4.0 V8 TDI, as found in the Audi SQ7, which produces 429bhp and 664lb ft. That’s the same output as the W12 already found in the Bentayga – but with top torque on stream from trifling 1000rpm.
What we’re looking at here is a prototype, but one with the refinement of a showroom car. Its engine is the same deep down as the SQ7’s, meaning it’s boosted by a supercharger and two turbos, but Bentley has tuned it to deliver its power with a smooth surge rather than a monstrous thump in the back.
The company’s engineers have also managed to make it almost silent and free of vibration, whether at tickover or under any sort of driving conditions you can think of. It might as well be a petrol engine – the only real difference is at the sort of speeds that lose you your licence in the UK, where the W12 keeps on pulling hard once the diesel’s race is run.
Our brief stint behind the wheel of this prototype lasted all of forty miles, and most of them were spent accelerating as hard as possible at every opportunity in a bid to find any chinks in the TDI’s armour of refinement (we failed). The result was 25.7mpg on the trip computer, which isn’t the 35.8mpg Bentley claims but might be under normal conditions. With what Bentley calls ‘state of the art’ emissions management, too, the Bentayga Diesel complies with all current and known future regs.