Motoring review: Bentley Continental GT Speed is faster than your average Beluga whale

Price: £151,000
Engine capacity: 6.0-litre, twin turbo-charged W12
Power Output (BHP @ rpm): 616 @ 6,000
Top Speed (mph): 205
0-60 mph (seconds): 4
Fuel economy (mph): 19.5
CO2 emissions (g/km): 338

How fast is fast enough? If you are Bentley the answer to that question is 205mph exactly. That's the top speed of the Crewe-based firm's new Continental GT Speed. It's a staggering turn of pace for a road-going car, even one as luxurious as this continent-crossing grand tourer. The technical challenges alone are mind boggling, before you begin to start to think about where this sort of straight-line speed is actually achievable.

The aerodynamic stresses are incredible. I'm told that at 205mph the side windows are sucked out with such force that the A pillar has had to be reinforced and Bentley had to design special seals to keep the glass in place. Meanwhile at that speed the car is swallowing up somewhere near 4,000 litres of air a second so the firm's engineers have had to incorporate all kinds of chassis and down-force black magic to keep it on the road. This is before you start to think about the uprated suspension springs Bentley has had to fit or the vice-like brakes required to stop it.

There's something even more amazing about all of this though; the GT Speed is still a properly civilised car to drive and spend time in. Its 616bhp engine – up from 576bhp in the standard Continental – is monstrous but it hasn't ruined the car. Don't get me wrong: the GT Speed is still a total weapon and only my caution and its four-wheel drive system keep me planted on my icy test route through the New Forest, but it's still a seriously luxurious and refined four-seater.

Unlike many 2+2 coupés, two adults can actually survive in the back and with a supple suspension and peerless noise suppression its touring manners are terrific. Inside the only letdown on my test model is the beluga hide, which hints at Bentley's bling footballer clientele. I worry I've become complicit in the slaughter of a rare arctic whale, but thankfully it's just named after the caviar, so I'm only guilty of awful taste.

There is one major issue that arises from all the power under the GT Speed's bonnet, though. When you are pressing on with your foot down into a corner there's so much puffed-up air in the engine's intake system that when you take your foot of the accelerator, that air has still got to work its way through the engine. There's a second delay when you take your foot off the throttle and the car continues to surge forward. You soon get used to it, though, and what else do you expect from the fastest Bentley ever made?

Never mind that you can only use a third of the GT Speed's power legally on the road, the Continental is the car that saved Bentley when it was launched 10 years ago and more than 42,000 have been sold since then. The new Speed GT is the apogee of the company's revival and in sport mode – with its throaty roar and pops and crackles on the overrun – it is a wondrous thing. There's just one problem. You could opt for the smaller-engined V8 version from the Bentley stable. It still produces 500bhp and will hit 180mph. In what world do we live when this isn't fast enough? Perhaps I'm missing the point: if you are spending £150,000 plus on a motor you probably want it to be something you can brag about in the pub (or the Michelin-star restaurants pre-programmed into the Bentley's satnav). And the fastest ever Bentley gets some bragging rights. Did I mention it does 205mph?