The Bentley Continental GT is a fast car. Blink-and-you’re-breaking-the-law fast in fact. And that’s on a motorway.

It’ll hit 100mph in nine seconds though, come to think of it, if you did blink for that long it would be classed as shutting your eyes, something you might well be tempted to do as the 633bhp and 620lbft of torque provides crushing evidence of Newton’s Third Law.

There’s something both beautifully primitive and yet remarkably civilised about the way the GT Speed goes about its business.

It almost certainly takes great pleasure in slamming you back into your seat as it launches its two-and-a-half tonnes forwards with effortless brutality, but the monstrous twin-turbocharged six-litre W12 remains caged behind an impenetrable wall that reduces its roar to a muffled, distant, rumble.

The more you demand from the glorious 12-cylinder motor the more it delivers. There’s a relentlessness about the power delivery that is guaranteed to drop jaws.

The higher the revs climb, the harder the car pulls and, just when you think it’s given all it has to give, the superb eight-speed box steps in and, with the silent efficiency of a hired assassin, calmly dispatches another gear.

Don’t imagine, however, that its mass scuppers any ambitions the GT Speed has of being a cross-country missile. Switch the adjustable dampers into sport setting and it corners with an agility that belies its size.

The nose pitches down sharply under heavy braking as the mass shifts to the front of the car but turn the front wheels into the corner and the rest of the car follows faithfully behind.

The steering is beautifully judged too. It suffers from a lack of feel but it’s quick, and direct, and the excellent weighting more than compensates for any disconnect between driver and road.

You can carry a huge amount of speed into corners and the 21-inch alloys shod with generous rubber bite into the tarmac with immense tenacity. Once the suspension has won the initial tussle with the car’s mass it flattens out, ready for you to launch it towards the next bend.

If you really want to fully take charge you can slip the gearbox into manual mode and use the paddle shifters mounted to the steering column – not the wheel, so they don’t move – and why not, because their burred backs feel delightful to the fingertips.

For all its surprising litheness, however, the GT is exactly that, a grand tourer, and it devours motorway miles like a hungry bear that’s just emerged from hibernation. It cruises along effortlessly, the cabin bathed in serene silence.

And what a cabin. You can, of course, opt for any combination of leather, wood and aluminium. My test car arrived with Burnt Oak hide with contrast stitching in Cumbrian Green. The fascia panels, centre console and roof console were finished in dark tint aluminium.

Changes to the GT Speed for 2016 are subtle, but then the Continental has always been a handsome car that has simply got better-looking with age. Inside they amount to revised seat quilting on the standard Mulliner spec interior, larger paddle shifters and some new dials.

Outside the new Speed wears the new family front bumper, a bespoke diffuser and rear spoiler that is stowed discreetly between the base of the rear windscreen and the top of the bootlid.

It rises automatically as your speed increases or you can manually deploy it with the press of a button. Behind the front wheel arches sit B-styled vents and below that, just above the sills one word that sums up this mighty automobile perfectly: Speed.

The GT Speed is expensive to buy, expensive to run and, undoubtedly, bad for the environment and that should be enough to stop me wanting one. But it’s not.

Bentley Continental GT Speed

Price: £168,300

As tested: £203,210

Engine: 6.0-litre W12 twin turbo

Transmission: 8-speed automatic

Max power: 626bhp

Max torque: 620lbft

Max speed: 206mph

Acceleration (0-60mph): 3.9sec

For more information visit www.bentleymotors.com