Bentley’s headline claim for the Bentayga is that it’s “the fastest, most powerful, most luxurious and most exclusive SUV in the world”.

Ten months ago, we reported that there was just enough permeability to an almost watertight fulfilment of that brief to justify denying the W12 a half-star’s worth of recognition.

Matt Prior

Matt Prior

Road test editor
Interesting to compare interior measurements on Bentaygas with and without the two-seat rear cabin…

On paper, the Diesel comes to market with almost 30 percent less power than the W12 and priced at £25k less – facts that don’t immediately promise it will satisfy at least 50 percent of the Bentayga’s mission statement any better than its rangemate.

But a delve into this car’s particulars reveals some of the ways in which it might upstage its petrol counterpart.

Torque is the first of them. The 3956cc ‘triple-charged’ V8 in the Bentayga Diesel produces precisely the same 664lb ft as the 5950cc twin-turbo W12 in the regular Bentayga. But while the W12 needs 1350rpm on the tacho to make it, the V8 diesel has it on tap from just 1000rpm, or, as near as makes almost no difference, from idle.

That should make it stronger and more flexible on in-gear acceleration than the already flexible W12 and could be an even bigger boon for towing, crawling and other things that big SUVs are commonly asked to do.

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The eight-speed automatic gearbox in the Diesel is identical to the one in the petrol, right down to individual gear ratios and final drive. Like the W12, the Diesel sends its power to all four wheels via a Torsen centre differential and an open rear differential, with electronic torque vectoring doing some of the job that a locking axle diff might otherwise do.

Bentley’s modifications to the Audi V8 diesel are confined mainly to ECU software changes.

Anxious that this car sounded and felt like a Bentley first and a diesel a distant second, Crewe’s engineers have softened the sound of the V8’s combustion and fitted ‘intelligent’ engine mounts and lined the engine bay and transmission tunnel with even more insulation than a W12 gets.

Fans of the Audi SQ7 may wonder why that car’s four-wheel steering system and its optional locking ‘sport’ rear diff haven’t been adopted.

According to Bentley engineering chief Rolf Frech, it’s because the systems “aren’t mature enough” to suit the character of a Bentley yet – “but we never say never”.

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