Meet the world's fastest and most expensive SUV, the Bentley Bentayga.

After teasing with overseas test drives, the first example has finally arrived on Australian roads.

Fewer than 50 will be delivered locally by the end of this year, and the queue already stretches into early 2017 -- despite the eye-watering price, which is the equivalent of two Range Rovers, and then some.

At close to half a million dollars ($494,009 as tested) the Bentley is proof there are still no bounds -- financial or technological -- to the world's love affair with SUVs.

With a top speed of 301km/h that would outpace most Porsches -- and a 0 to 100km/h sprint time that would see off most Ferraris -- the Bentayga brings the world of SUVs to a new level.

A Breitling clock in the dashboard costs almost $300,000

It shares its underpinnings with the new Audi Q7 and its engine is derived from the one used in Volkswagen's recently discontinued flagship limousine, the Phaeton.

The ingredients are then wrapped in a Bentley design package, which is an acquired taste -- which I'm yet to acquire.

Why on earth does the automotive world need such a machine? That wasn't the only question we pondered.

It also has the dubious honour of having the world's most expensive car accessory.

A Breitling clock in the dashboard costs almost $300,000 -- on top of the car's $494,009 price tag.

Oh, and there is already a digital clock in the car's instrument display.

Bentley claims Breitling can only build four of these particular in-car clocks each year, and two are already sold. None are on Australia-bound cars, apparently.

Other accessories: a $55,000 picnic hamper, a $10,000 leather-lined child seat and $6500 for a dog cage in the back.

Radar cruise control is part of a $15,465 "touring" pack while floor mats are $972.

Sensors that enable you to open the tailgate when your hands are full -- with a deft one-legged swing of your foot under the bumper -- are a $1702 option on the Bentley, even though they are standard on a $40,000 Ford Kuga.

A cigarette lighter is $1151. The price of luxury.

The brute force of this engine is available almost instantly

But the Bentayga has an engine like no other SUV on the planet: a twin-turbo 6.0-litre W12 (W is not a typo, it's two V6's mounted back to back, in the shape of a W rather than a V).

Paired with an eight-speed automatic transmission and all-wheel-drive it's one of the key reasons Bentley has seemingly been able to defy physics and move 2.4 tonnes over a short distance in a very short amount of time.

Curious to see how close we could get to the claimed 0 to 100km/h time of 4.1 seconds (equal fastest with the Porsche Cayenne Turbo S), we were stunned to find it got to 4.2 seconds with relative ease after a few attempts.

It was all the more surprising because -- as hard as this may be to believe -- it does not feel particularly fast.

That's because the brute force of this engine is available almost instantly, and layers of sound deadening make the whole experience almost hush quiet.

Your senses aren't startled by a raucous engine and exhaust note, but your body knows something isn't quite normal because your neck muscles are working overtime to stop your head from snapping backwards from the sudden acceleration.

Its cornering ability is a bigger highlight than the engine power

The next surprise that defied the senses was the Bentayga's ability to corner more nimbly than physics ought to allow such a big heavy car.

The massive 22-inch wheels wrapped in sticky Pirelli P Zero tyres help work wonders, as does the well sorted air suspension.

To be frank, its cornering ability is a bigger highlight than the engine power. And that's saying something.

Downsides? There is still a question mark about European reliability; Bentley is owned, after all, by the giant Volkswagen Audi Group. Our test car, a pre-production model, had an error warning light for the suspension although we were assured nothing was wrong and it drove ok.

If it's any consolation, customers get free business class travel to their destination if the car breaks down while under warranty.

I went into the Bentley Bentayga with low expectations and came away dumbfounded by its breadth of capability -- even if you won't get far off the beaten track should you need to use the space saver spare.

For all its merits, however, it is difficult to justify the cost.