Video: Bentley Continental GT Speed review The energy flows are boggling. At top speed, the 6.0-litre, W12, twin-turbo engine emits 260kW of engine heat, which is dissipated with 4,000 litres of air passing through the radiators every second. A full-power stop from that speed requires 10 megajoules of energy to be dispersed as friction heat; that's enough to light the average UK house for six hours. Yet, while wild horses will never drag from me where I did it, back in 2003 when I first drove the original Continental GT with a paltry 552bhp on tap, I saw well over 200mph on the speedometer. "We're always conservative in our claims," said Ulrich Eichhorn, Bentley's chief engineer at the time. With this new GT, however, there are some drawbacks to this extra velocity. If ever there was a car not requiring eight gears, then this is it. Bentley claims it improves the car's fuel consumption in EU tests, but that's pretty academic to owners and the environment, and the high top gear, which pulls almost 46mph per 1,000rpm, enables that top speed. But even if you drive it in normal automatic mode, the car hunts between ratios, which flies in the face of the effortless Gran Turismo. There's also a lot of puffed-up air in the flues between the turbos and the inlet valves. Charge up to a corner and lift off the throttle and the car doesn't start to slow for a nerve-jangling half second - on wet roads make that a terrifying half second. You get used to it, but it does make the Speed feel like a runaway train. The sports exhaust is plain unpleasant, booming and resonating with a nasty high-pitched whistle, so you tend to avoid sports mode, especially as it makes the gear change uncomfortably abrupt as well. Riding on uprated air suspension with stronger springs and damping, there's a slight nervousness even in the softest comfort setting. The Servotronic hydraulically assisted steering has also been tweaked, but although it's accurate and well weighted, it's as dead as a mallet in your hands. If you drive too fast into a corner, the nose goes straight on while the stability systems buzz like beehives trying to brake the car back into line. Plant the throttle and, on a wet road, the rears slide wide, but eventually the front wheels pull the car straight. Inside the cabin, there's the usual herd's worth of hides, coppice's worth of veneer and magpie's nest of shiny chrome. The meld of modern and tradition is pleasingly successful and the winged-shaped dashboard has a new satnav and (at last) a DAB radio. The Speed's front seats are comfortable and supportive, and allow a bit more room in the back. You'd never tire of sitting in a Bentley Continental, but that applies as much to the standard cars as it does to this Speed model. With a premium of £12,700 over the standard W12 GT and £26,100 over the V8, I think the Speed customer is paying too high a price. Put simply, there are better cars available and some of them even have Bentley badges. Bentley Continental GT Speed Tested: 6.0-litre, twin turbocharged W12 petrol engine, eight-speed ZF automatic transmission, all-wheel drive Price/on sale: £151,100/now Power/torque: 616bhp @ 6,000rpm/590lb ft @ 2,000rpm Top speed: 205mph Acceleration: 0-60mph in 4.0sec Fuel economy: 12.7mpg/19.5mpg (EU Urban/Combined) CO2 emissions: 338g/km VED band: M (£1,030 first year, £475 thereafter) Verdict: All the good stuff remains, but in pushing the engine this far Bentley has ended up affecting the driving experience for the worse. Disappointing in comparison with its forebears Telegraph rating: Three out of five stars Aston Martin Rapide Luxe, from £162,8007 Elegant extension of Aston's long-running VH chassis is deceptively spacious. The 470bhp, 6.0-litre V12 performs well, with sharp ride and handling, but cabin is dated and it's expensive. Ferrari FF, from £227,107 This is a 650bhp, 6.3-litre V12, 4x4 hot rod, with four seats and a boot. Innovative drive to the front wheels as well as the traditional rear-drive set-up, but it does affect the handling. Mercedes-Benz CL 63 AMG, from £163,825 The Cinderella of luxurious coupés, but exclusive and unobtrusive. The 630bhp, 6.0-litre twin-turbo V12 sounds like a powerboat. Cramped in the rear and the low-speed ride is noisy.