Motoring editor Andy Russell takes on the huge responsibility of being a Bentley boy... if only for a weekend.

Suddenly it hit me, but fortunately it was the realisation of how much this car was worth rather than an actual collision.

We were wafting along when, without warning, my son announced: 'You're driving a three-bedroom house!'

Well, actually I was driving Bentley's new performance flagship, the Continental GT Speed which starts at £152,600 but the model I was driving had risen to £186,400 with options... some £6,000 more than the three-bedroom semi he had agreed to buy two days earlier. The value of the car was scary but so is the fact my 'little boy' is about to become a homeowner!

I don't think I had ever been so excited or perturbed about a test car as I was with the imminent arrival of one of Crewe's finest.

Resplendent in its £3,295 rubino red paintwork option it was a real case of beauty and the beast – a marvellous motor with monstrous performance.

With its 6.0-litre twin-turbo 12-cylinder petrol engine uprated to 625PS, the GT Speed can reach 60mph from rest in four seconds, 100mph in just nine and go on to a potential 205mph, making it the fastest road car Bentley has ever made.

But for all its power, performance, and price it is incredibly easy to drive. Within a couple of hours I loved it and could understand why so many people see Bentley as the ultimate in motoring pleasure.

The noise of the W12 engine is phenomenal. Press the start button and it winds itself up and, bang, fires into life with a deeper, throatier growl than the other Continental GT two-door coupes.

Select drive on the eight-speed automatic gearbox and it just glides away in a refined and controlled manner but get it on the open road and press the throttle even slightly and it is like warp factor on Star Trek's USS Enterprise as 2.75 tonnes of luxury launches itself at the road ahead. And it stops as well as it goes, especially with the £10,405 carbon ceramic brakes option with 420mm front and 356mm rear cross-drilled discs which pull it up extremely sharpish.

Despite all that power, sensible driving (and you're not going to do anything else with a £5,000 contribution to Bentley's insurance excess!) it returned 25mpg on a run and 22mpg overall partly thanks to the engine running at just under 1,500rpm at 70mph – drive a lot in town though and you'll be in the low teens. That said, if you can afford a Bentley you're hardly likely to worry about filling the 20-gallon tank.

The GT Speed is not just about boosting power and performance. The chassis has also been enhanced with uprated springs, anti-roll bars and bushes, a 10mm lower ride height and retuning of the electronically-controlled damping, which switches between comfort and sport, and steering.

The Bentley is a big car but the handling is so good that it belies its size. You're unlikely to throw it around corners like a sports car but it hugs the road with huge grip from the all-wheel drive system, which is biased 60/40 toward the rear wheels, and fat tyres. But even with the dampers in the tauter sport setting and riding on the exclusive 21in wheels, the GT Speed soothes away poor surfaces uncannily capably and eerily quietly. This is a car you could drive all day and get out feeling ready to do it all over again.

The sumptuous cabin – supreme testimony to British craftsmanship, tradition and taste – is a tranquil haven of diamond-quilted perforated leather hides, chrome switches and features, stitchwork and wood or, in the case of my test car, carbon fibre panels. It even has an exclusive Breitling clock. As for comfort you just sink into the four bucket seats with just about enough legroom to carry adults in the back. And the 358-litre boot, trimmed with better carpet than in my lounge, will take their luggage.

The Bentley Continental GT Speed was a huge responsibility but an enormous pleasure once I got over the fear factor of driving the ultimate luxurious Grand Tourer.