I AM fortunate to be familiar with Bentley cars, having driven quite a few over the years.

Generally my recollections of the driving experience on each occasion behind the wheel are fond ones - the delight of driving such sublime pieces of British engineering excellence combined with outstanding craftsmanship live long in the memory.

However I also have memories, which I'm sure are not exaggerated over time, of being sure I can actually see the fuel gauge move, if and when the vehicle is being driven particularly enthusiastically.

Of course if you are a Bentley owner it's unlikely you are going to baulk at regular and hefty fuel bills - it pretty much goes with the territory.

But now there is a Bentley capable of travelling more than 600 miles on a single tank of fuel.

The reason for such extraordinary fuel efficiency in a marque not renowned for it is that this particular Bentley is a diesel.

Yes, you heard it right - a diesel.

The Bentayga Diesel is Bentley's first ever diesel car and quite an extraordinary beast it is too.

Of course it makes sense in so many ways to have a diesel version of Bentley's first SUV - the Bentayga.

Given everyone wants to get in on the SUV act, including the likes of Rolls Royce, Lamborghini and Maserati, I guess it's a natural enough thing - though no doubt some purists might consider it sacrilege.

It's still early days for the Bentayga but I genuinely believe it will prove a highly successful model for the brand, in the same way the Cayenne did for Porsche.

Of course it's hard to make an SUV look like a Bentley in the traditional sense but the Bentayga has enough familiar trademarks to carry it off.

Overall it is nicely sculpted from a design perspective and its imposing front end shouts Bentley from the rooftops. The rear has just a hint of coupe styling but enough to set it apart from most SUVs.

On the inside the Bentayga really is 100 per cent Bentley. Traditionally styled instrumentation with modern functionality, beautifully crafted wood inlays and splendidly sculpted leather seats combine to create an environment that is very much a country club on wheels.

Passengers in the rear are comfortably catered for too. If you want to transport them luxuriously then it's probably best suited to two passengers, though there are three seats which adds to the Bentayga's practicality.

Rear seat passengers can also enjoy the Bentley Entertainment Tablet - a removable 10.2-inch Android device with 4G, Wi-Fi and Bluetooth.

So, what of that diesel engine which really is a ground-breaker for Bentley.

It's a triple-charged, 4.0-litre, 32-valve V8 engine developing 429bhp.

There's no disputing it's one hell of a performer, with a top speed of 168mph.

Acceleration is blistering too and it will take you from 0-60mph in just 4.6 seconds.

Crucially it both feels and sounds very un-diesel-like and delivers a deliciously throaty roar when you put your foot down.

Impressively it is extraordinarily refined and well insulated too. From the driver's seat there is little indication that you are in fact driving a diesel, particularly from a performance point of view.

That's hardly surprising, given the performance figures aren't really all that different to the 608bhp W12 petrol model.

The only huge difference is when it comes to fuel economy, with the diesel managing a combined figure of 35.8mpg while with the petrol it is just a paltry 21.6mpg.

So, what's the driving experience like?

There's no disputing the Bentayga is a big and heavy vehicle. Each time I drove on to and off my driveway I felt I needed to do so with precision and care - there was enough space but not a huge amount to spare between a wooden fence with concrete posts on one side and a brick wall on the other.

Out and about though it has a nimbleness and agility that takes you by surprise. It's hugely fun to drive and you soon get used to those dimensions. The steering offers plenty of feel and its lightness makes the car easily manoeuvrable.

The ride is incredibly comfortable and you can adapt how the car feels and performs - and copes with a huge variety of terrains - through the multi-mode traction control.

Of course the Bentayga isn't cheap but if you're comparing it to something like a Mulsanne then it's around half the price of some versions.