THERE'S only one thing to do with the fastest production model ever built by Bentley - you give it even more muscle.

That's what happened with the ferocious Continental GT Speed some months ago when the Bentley Boys raised the bar another notch, with more power and torque.

So much so that the Conti's 6.0-litre twin-turbocharged W12 engine now produces 642ps - up from 635ps - and 20Nm of extra torque, bringing its total to a mountainous 840Nm.

The extra pulling power spans the rev range and raises the Grand Tourer's plateau of continuous maximum torque delivery from 2,000-5,000rpm, bringing greater acceleration.

It means the car's 0-60mph sprint time has dropped to an eye-popping 3.9 seconds, delivered via a close-ratio, ZF eight-speed automatic transmission.

There's nothing frenetic of course because the Speed is a supreme traveller, beautifully refined, supple and civilised while capable of block-shifting during downchanges - flicking from eighth to third gear in an instant.

Anyone with the lolly to bag a Bentley will be free of economy concerns, which is just as well because realistically they aren't going to do much better than around 15mpg in everyday driving - so the downside is only going to be the inconvenience of filling up.

But whether powering majestically along the motorway or picking out a relaxed route through suburbia, the Speed is a true thoroughbred.

Exquisitely appointed in every way - from the Breitling analogue clock on the dash to the perforated, quilted soft leather seats with ‘Speed' embossed in all four individual headrests - the Continental carries an air of total distinction.

In fact it takes 110 hours to handcraft every Continental GT at the Bentley factory in Crewe and the upgraded W12 engine applied to all GT Speed models is entirely assembled by 30 specialist workers over 12½ hours.

This sort of craftsmanship, and the technology applied to cars like this doesn't come cheap - nor does the status of owning a Bentley, let alone the fastest one the Cheshire brand makes.

So it shouldn't come as a surprise that a few key options can hike the tab considerably.

In our case the £168,900 on the road price topped the £200K mark courtesy of items like carbon ceramic brakes with black painted calipers at £10,825, adaptive cruise control (£2,125), a digital TV tuner (£920) and dark tinted aluminium panels (£3,810).