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Crewe’s first diesel-fuelled production car strives for SUV perfection

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Bentley Motors Limited will celebrate its centenary before the end of this decade.

So far in its near hundred-year life it has moved twice, been sold twice, been bought three times, won Le Mans six times and made large, luxurious and exclusive passenger cars as different as the 1971 Corniche convertible, the original 1985 Turbo R and the landmark Speed Six of 1928.

I like the combined starter button/drive mode selector, not least because of its Bentley mode. Saves you shouting “Just set the thing up like the chief engineer would have it!”

The firm’s history has been short on neither boldness nor incident, but the past two years have brought greater and more contentious change than the preceding 96 did.

To the disgust of some and the delight of others, Bentley now makes a high-sided sports utility vehicle: the £163,000, 2.4-tonne, 600bhp Bentley Bentayga W12.

And no doubt equally appalling to traditionalists, Bentley has just introduced a new engine for the car they already hate. The Bentayga Diesel becomes Crewe’s first ever diesel-engined production model.

The source of the diesel engine is as contentious as the fuel it quaffs: Audi’s factory in Gyor, Hungary. The 4.0-litre V8 multi-stage turbodiesel motor is materially the same as the one used by Audi’s Audi SQ7.

So while owners of a Bentayga W12 can claim that the beating heart of their car is every bit as ‘Bentley’ as the walnut veneer on its fascia, buyers of this version won’t be able to follow suit.

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The engine capitalises on the Bentayga’s 48V electrical architecture to even greater profit than the W12.

It uses twin sequential turbochargers and a smaller electrically driven compressor, the latter primarily to take driveability to new heights and banish any vestige of turbo lag. The electronic governance of the engine and the particulars of its installation are all Crewe’s own work.

So is this a Bentley to be welcomed?

Is it good enough to win over those at once sceptical that an engine such as this belongs in a Bentley and that the winged crest should adorn an SUV?

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DESIGN & STYLING

Bentley Bentayga Diesel rear

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.

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 Bentley 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.

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”.

INTERIOR

Bentley Bentayga Diesel interior

Cabin appointment – working with wood, leather and metal to quite breathtaking effect, and applying standards and techniques that no other car maker could hope to match – is what Bentley does best.

Under Volkswagen’s careful custodianship, this has become Crewe’s gift to luxury car making.

…three-seater versions have slightly more rear leg room and almost 100mm more boot length behind the seats

This is our second acquaintance with a Bentley Bentayga’s cabin, and yet that bit of familiarity didn’t make sitting in the Bentayga Diesel any less of an event.

The driving position is far from typical of a large SUV’s. It’s only moderately high, although widely adjustable and superbly comfortable – so if you want a more lofty view of the road, you can have one.

Leave the seat in a typical setting, though, and you get an almost perfect balance of cocooning and commanding impressions from behind the wheel.

The door consoles rise higher at your side than you expect them to. The window profile above that is slimmer than in a traditional SUV and the roofline just a touch closer to your scalp (although head room remains beyond reproach).

The effect is of a cockpit that you might imagine belonged to an exotic saloon, albeit one suspended at least a foot above where it ought to be on the road and a generous cut above what’s happening beneath.

The main control interfaces include a large, chromed, no-nonsense gear selector that is well placed and easy to use.

Behind that is a rotary dial that doubles as a push-button engine starter button and, by twisting it, allows you to cycle through the Bentayga’s various ride, handling, traction and stability control modes (including Sport, Comfort, Custom, Snow, Sand, Forest and Track). Grouping those drive modes like that is particularly clever because the starter button is always going to be an important point of contact for the driver, and giving it a secondary job somehow makes flicking between modes feel more intuitive than it might.

Complaints are so few in number as to hardly deserve a mention. Pedants might point out that there are Audi parts bin column stalks and headlight controls in evidence, solid and pleasant though they are. Honestly, we very much doubt Bentley could have sourced better.

The Bentayga’s infotainment conforms to luxury-class convention by being fairly discreet in its scope and proportions.

You can spend much less on a Mercedes-Benz, Audi or BMW with a larger and more feature-rich multimedia set-up — and that’s very much intended. In Crewe’s world of opulence and calm, the neon glare of technology is often best shut out.

Even so, the car comes with an 8.0in touchscreen with built-in nav, 11GB of storage, DAB radio, a CD/DVD player and the capacity to turn a 4G smartphone into a wi-fi hotspot.

Pay extra and you can add a digital TV tuner (£965), and two 10in rear-seat entertainment tablets (£5635) that mount on the back of the front headrests or can be removed to act like standard tablets. Our test car had Bentley’s Naim-supplied premium audio system (£6615), too.

Changeable digital reception made the TV add-on a bit pointless, but the premium stereo and rear-seat tablets  impressed. And while many would jolt at the idea of paying more than £12k to upgrade a multimedia system, Bentley says its customers don’t.

ENGINES & PERFORMANCE

4.0-litre V8 Bentley Bentayga Diesel engine

This engine, in slightly different states of tune, has gone up against our road test benchmarking gear twice already, in the Audi SQ7 and the Porsche Panamera.

We knew, therefore, how unlikely it would be to let Bentley down, even allowing for the Bentayga’s 2645kg weight and Crewe’s standards on driveability and mechanical isolation.

Power-on understeer forces you to deploy engine torque gradually on exit

What we didn’t reckon on were where those standards would take this car above and beyond the refinement we’ve already experienced elsewhere.

The Diesel is astonishingly smooth and quiet. Its V8 declines to send any of the shudders that a compression-ignition engine can transmit into the cabin on start-up, and it settles to a remote, demure idle that isn’t even faintly clattery or brusque.

Frankly, it’s barely audible. The engine raises its voice just loud enough to hear it as you move off but remains pleasant and sweet-sounding as it spins faster, and even at high revs it never intrudes.

Bentley’s W12 is a little more tuneful when worked hard, but the difference between the two engines on tonal richness is remarkably small.

The W12 does move the Bentley Bentayga a bit more forcefully at times, but only when the accelerator is on its stop and the tacho needle is spinning to the redline, which is a mode that you’d expect Bentayga owners rarely to adopt.

To hit a flying 100mph from standing, the Bentayga Diesel needs exactly a second longer than its 12-cylinder rangemate and more than two seconds more than a Range Rover Sport SVR.

But to spirit itself from 40-100mph in sixth, which is a much more telling measure of accessible on-road pace, the Diesel is 1.4sec quicker than the W12 and more than four seconds quicker than the SVR (and with another 60mph still to gain before it needed another gear).

You can imagine how easy that performance would make motorway driving and the towing of heavy trailers, and in what kind of incredibly relaxed style the Bentayga Diesel could pick off slower cars on well-sighted A-roads.

Laid-back, suave, rich and luxurious-feeling pace is absolutely the kind that Bentley’s SUV should provide – and this one has it in glorious abundance.

RIDE & HANDLING

Bentley Bentayga Diesel cornering

A dash of additional nose weight and a smidgeon of extra tyre sidewall would appear to have effectively addressed our criticisms of the slightly busy and occasionally fidgety ride of the Bentley Bentayga W12.

The Diesel was supplied on 21in wheels (the W12 we tested was on 22s), and Crewe’s claimed kerb weight has it at 32kg more than the petrol model – a difference attributed to the iron block and relatively complicated induction system of that diesel V8.

Leave the car in Snow and Ice mode and the ESP is in an almost constant but discreet state of intervention

There is also a bespoke software tuning for the car’s air suspension, adaptive dampers and active anti-roll bars here, of course, intended to give the Bentayga Diesel a dynamic character all of its own – and very likely a slightly softer and more supple one than the W12 has.

Whatever the cause, the result is a Bentayga that massages away an even wider variety of lumps, ridges and bumps that travel under its wheels than the last one we tested, and which, driven at just the right pace, could convey you hundreds of miles on a mix of surfaces while maintaining a near perfectly cradled and consistent sense of isolation.

The Diesel’s ride does permit some surface noise into the cabin: just a faint background road roar, amplified a bit, no doubt, by the air spheres suspending its hubs. But even allowing for that distant hum, the car is supremely supple and quiet.

A matching sense of isolation can be felt through the steering wheel, which acts more directly on the car’s front wheels than most SUV owners will be expecting.

Even in Sport mode it’s typically short on feedback and suffers with slightly wavering weight during hard cornering, but at least in the former respect, that’s how Bentley owners will want it.

Contrary to what the car’s sheer heft and light control weights lead you to expect, the Diesel’s body control is surprisingly flat and very smartly reined in when pitched into a bend.

It’s much gentler when tracking straight (particularly in Comfort mode), though, and while it allows plenty of vertical movement over larger undulations, it seldom permits the considerable mass to rebound unchecked.

Grip levels are always high, stability is strong, handling response is excellent and the car reacts well to being driven quickly when the mood takes you.

Despite a marginally softer-riding character than its sibling, the Diesel remains a better-handling and more engaging prospect than almost anything else that offers the same amount of luxury, or almost any other SUV of a similar size.

While heavier than the W12 and lacking some of the active chassis systems of the Audi SQ7, the Diesel was the most balanced and controllable on track.

On steel discs, with so much mass to slow down, the brakes don’t last long on a circuit. Long enough, though, to prove that grip and body control are good enough to stand proper scrutiny.

The Bentayga will pull 1.11g of lateral cornering load — comparable with a hot hatch or sports saloon — and maintain well-balanced grip and well-contained roll in steady-state cornering.

Traction and stability control systems prevent the powertrain from disrupting grip too much, but turn them off and it’s easy to trigger understeer if you’re impatient on the throttle. The benefit of disabling the ESP, however, is unexpected adjustability on a trailing throttle.

Active anti-roll bars help to shift the car’s mass and unload the rear axle when you lift off quickly in a bend.

MPG & RUNNING COSTS

Bentley Bentayga Diesel

The most important figure to note here starts with a ‘3’ – but could reasonably be approximated to a round ‘40’ if you wanted to sum up neatly the real-world touring economy you could get from this 429bhp, 2.6-tonne luxury SUV.

As unlikely as it may seem, the Bentayga Diesel returned 38.9mpg on our touring test. That is a better result than the Audi SQ7 (which was also on 21in alloys) achieved in its road test, and a figure that makes the oilburner almost 60 percent cheaper to fuel than its petrol equivalent.

Strong predicted demand should lead to outstanding residuals. W12 version is 7 percent worse over three years

Those planning to use their Bentayga every day will appreciate a range that could exceed 700 miles – having to stop at the services for a 1am splash and dash after a long day’s driving is, after all, considerably less luxurious than not having to.

Depreciation is a familiar cost for plenty of Bentley owners, but now the firm’s ‘approved used’ programme is in place, things are changing.

CAP expects the Diesel to do very well on residual value and, bought now, to hold on to a greater proportion of its showroom price over three years and 36,000 miles, starting at that £135,800 list price, than an Audi SQ7 does from just under £72,000.

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VERDICT

5 star Bentley Bentayga Diesel

So the Bentley Bentayga - its dynamic foibles so adroitly corrected, its ownership case strengthened and its engine bay furnished with a ‘triple-charged’ V8 diesel that makes it more frugal, more usable, more muscular, more fit for a luxury SUV’s purposes and still just as refined – becomes our second five-star car of the year.

A critic might say it’s empty praise, with so few established super-luxury SUV rivals yet available to set a standard.

Bentley’s vision of the perfect SUV gets its missing piece

But to deny Bentley the recognition it deserves on that basis would be to ignore the commitment it has shown to get into what will soon enough be a well-populated market niche.

It would also underplay the risk it has taken in using its VW Group connections to broaden the reach of its line-up by adding a diesel string to its bow in the faith that its expert engineering team would make sure it felt like no ordinary diesel.

This car rises head and shoulders above any other in fulfilling the role of the consummate, complete, luxury SUV.

And in five years, when there may be rivals from Rolls-Royce, Aston Martin, Lamborghini and others, we won’t be surprised if it still does. But for now it tops our list ahead of its closest competitors in the shape of the Range Rover Sport SVR, Audi SQ7, Range Rover SV Autobiography and Mercedes-AMG GLS 63.

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Matt Saunders

Matt Saunders Autocar
Title: Road test editor

As Autocar’s chief car tester and reviewer, it’s Matt’s job to ensure the quality, objectivity, relevance and rigour of the entirety of Autocar’s reviews output, as well contributing a great many detailed road tests, group tests and drive reviews himself.

Matt has been an Autocar staffer since the autumn of 2003, and has been lucky enough to work alongside some of the magazine’s best-known writers and contributors over that time. He served as staff writer, features editor, assistant editor and digital editor, before joining the road test desk in 2011.

Since then he’s driven, measured, lap-timed, figured, and reported on cars as varied as the Bugatti Veyron, Rolls-Royce PhantomTesla RoadsterAriel Hipercar, Tata Nano, McLaren SennaRenault Twizy and Toyota Mirai. Among his wider personal highlights of the job have been covering Sebastien Loeb’s record-breaking run at Pikes Peak in 2013; doing 190mph on derestricted German autobahn in a Brabus Rocket; and driving McLaren’s legendary ‘XP5’ F1 prototype. His own car is a trusty Mazda CX-5.

Bentley Bentayga Diesel 2016-2018 First drives