Road Test: Bentley Continental GT 6.0 W12 Speed 2dr Auto

This Continental GT Speed is Bentley's fastest-ever production car, hitting 60mph from rest in 4.0secs and a whopping 205mph top speed, but really we're talking about marginal differences in an already rarefied atmosphere. After all, the standard W12 manages the sprint in an already-rapid 4.3 seconds and hits 197mph flat-out, so clear daylight was always going to be hard to find. But let's not quibble - the Speed is brutally fast, pulling hard at the 174mph we achieved on the autobahn, with 205mph feeling entirely possible.

Its effortless nature is down to massive reserves of power (616bhp) and torque (590lb ft), up 49bhp and 74lb ft from the standard W12, thanks to fairly traditional tweaks to the ECU and exhausts, as well as increased turbo boost and a new eight-speed automatic 'box. So far, so predictable. But that's not to say it doesn't work.

The new gearbox is excellent (now available on the standard W12), capable of block-shifting during downchanges, meaning the Speed can easily jump from eighth to third, resulting in rapid kickdown. Along with all that power and torque, overtaking is never an issue. It also sounds more demonic, the exhaust having been retuned to resonate more deeply as well as flowing more gas, and if you drop the 'box into Sport or Manual, extra baffles are opened for the full blare. It's got a brutal bass note which sounds brilliantly threatening.

Not that this is a scary car to drive fast. The Speed is still a GT at heart - comfort and luxury coming before out-and-out handling. The suspension has been stiffened and lowered by 10mm and the steering has been retuned, but don't go thinking it's taken on a different personality to the standard W12. Both cars are imperious to drive, extremely fast and give just about enough feedback, but weight and sheer physical size prevent either performing hot-hatch-type heroics over UK back roads.

So the Speed is a bit like a W12 with 10 per cent extra toothiness. Customers will love it simply because it's the fastest and most expensive Conti coupe, but if it were our money and we were being relentlessly rational, we'd have to recommend the smaller-engined - but still 500bhp - 4.0-litre V8. Just as everyday quick, £27,250 cheaper, and 7.2mpg more efficient. But then, who buys a Bentley to be rational?