| First Drive | Jerez, Spain | Bentley Continental GT Speed |

Aside from the rather showy 20-inch alloy wheels with their bespoke rubber there's little to distinguish Bentley's new Continental GT Speed from its lesser Continental GT relation. Indeed, the standard GT gains the same larger front bumper and chrome headlamp highlights of the GT Speed as part of its 2007 model year changes. Which begs the question: why spend the extra £17,000 the £137,500 Speed commands? Well, the clue is in the name. The Speed is able to reach 202mph, it being the first production Bentley to offer an official top speed in excess of 200mph.

That double ton ability has been achieved by liberating some extra power from the Continental's 6.0-litre twin-turbo 12-cylinder engine. And it hasn't simply been a case of adding a bit of boost to the GT's turbos. Bentley's engineers have given the W12 a serious overhaul. Inside there are now lighter con-rods, new pistons, improved cooling and less internal friction. There's been a bit of engine management reprogramming too, and the exhaust's catalyst breathes easier giving less back pressure. The combined result of all these changes is 600bhp at 6,000rpm, and 553lb.ft of torque. That's some 48bhp and 84lb.ft more than the standard car.

So it's the fastest Continental GT in outright speed, and unsurprisingly its sprinting ability has been improved too. Despite a hefty 2,350kg kerb weight the Continental GT has always been a remarkable sprinter, but the improvements to the GT Speed allow it to reach 62mph in 4.5 seconds, some 0.3 seconds quicker than the standard car. That difference is more or less the same throughout the entire range of performance increments, where the GT Speed feels a good deal more muscular due to its boosted torque.

There might not be much outside to highlight that the GT you're in is the hotter Speed, but start it up and there's unquestionably a more purposeful rumble from its freer-breathing exhaust. That's deliberate, Bentley wanting a harder-edged soundtrack to its more hardcore product. Yet it takes a while to really understand the changes on the road. Sure, it's a bit noisier, but drive it normally and there's little real obvious difference to the driving experience. The ride feels a bit more compliant, even when set to its stiffest Sport mode, the jarring you'd sometimes experience in the 'old' Continental GT when faced with ridges and cracks apparently no more.

That's an impressive trick in a more focussed car, and certainly the handful of people who'll buy the regular Continental GT on its smaller 19-inch alloys will appreciate the suspension changes even more. But who will that be? Who's really going to go into a Bentley dealership and order the cheaper, slower car? So it's likely that the Speed will take the majority of sales, and so it should, as it offers no obvious compromises over its standard GT relative - unless you're not a fan of those rather overt alloy wheels.

What it does offer is a sharper, more involving drive, that nicer soundtrack and a far more enticing interior specification. That includes, amongst other items, a smaller and neater steering wheel, quilted leather hide and embroidered Bentley emblems on the seats.

The only problem with the enhanced Speed is that to really benefit from the changes Bentley has made you need to drive the Continental GT Speed in a quite un-Bentley manner. Throw it down a winding road and the Speed reveals its greater agility. There's tighter turn in and even some feedback through that smaller three-spoke steering wheel. But you really have to be giving the Bentley a serious work out to uncover its greater breadth of ability. Do so and it changes direction with remarkable dexterity, while the optional (£10,000) carbon ceramic brakes wash off the speed it gains so easily with impunity. Drive it hard and you'll find yourself covering ground at enormous pace. That's moon-shot, rather than mere licence-threatening, pace. The fuel consumption's rocket-like, too though.

That's once you've gotten round the sometimes slow to react six-speed auto. Use the nicely positioned paddles, a fair bit in advance of when you might actually want the 'box to shift, and the Speed charges forwards with relentless urge. Watch the digital speed read-out and it racks up numbers like a Vegas casino slot machine counter when the OAPs are in town.

It's hilariously fast, yet still remarkably dignified and refined as a big GT should be. There's a massive boot (for the golf clubs, naturally) and room for a couple of passengers in the rear if it's a short, rather than continental, journey. And like its regular GT relative it's beautifully built. The interior is a tactile delight; we doubt anyone could ever tire of opening and closing the organ-stop chrome pulls for the ventilation; everything inside trimmed in the finest materials. Make no mistake; the Continental GT Speed is a very desirable car. It's just a bit of a shame that its enhanced driving talent is so far up in the echelons of its performance that few will ever really be able to enjoy its rather extraordinary ability.