Four years ago Bentley promised a powertrain for the Continental GT that delivered 40 per cent lower fuel consumption and emissions than the W12 system of the day. The result is finally here, and while its raison d\'être is efficiency it also represents something more exciting than that. The reality these days is that cutting-edge efficiency technology has become a selling point even to buyers with the means to pay ‘whatever it costs\'. In building a supremely high-tech, much less environmentally unfriendly engine Bentley has incorporated some of the most advanced efficiency techniques available for internal combustion — within the boundaries of what their customers really want. After years of painstaking development the result is a 4.0-litre V8, two litres smaller than the W12 and cleverly turbocharged to deliver a huge 500bhp and 660Nm kick. Its most intriguing facet is what Bentley calls variable displacement. It\'s a cylinder shut-off system that, when the engine is under low loads, cuts fuel to four of the cylinders to leave a 2.0-litre V4. Pressing the accelerator brings the other four pistons back to life, and what\'s really remarkable is that you just can\'t feel it working. It\'s crucial, though. Without it there\'s no way a range of over 800km would be possible from a 90-litre tank of super unleaded. There are plenty of technological flourishes in the engine and gearbox, like mounting the turbochargers inside the ‘V\' of the engine to save weight and keep the key air flow pipes as short as possible. That way the turbos respond more quickly and on the road there\'s no noticeable lag at all — remarkable for a 2.3-tonne car (nearly 2.5 for the convertible GTC). There\'s also very little wind noise, whichever version you\'re driving. The GTC, which is available from launch alongside the coupé, is every bit as quiet inside. It\'s very easy to forget it\'s a soft-top until you\'re outside the car again. The roof also looks great whether it\'s in place or folded away, which can\'t be said for all of its rivals. Refinement is a big deal at Bentley, and certain well-known efficiency tech has consciously been left out because it\'d take away from the element of luxury. It has the well-known and brilliant ZF eight-speed automatic gearbox but you won\'t find stop-start, eco change-up indicators or any other motoring equivalent of whale music. What you will find is a different character entirely to the W12. The Continental GT is a grand tourer, as per the name, but the GT V8 would better fit a ‘grand sports tourer\' tag. It\'s deliberately a little bit cheekier than its older brother. It\'s fair to say that performance is astonishing from a standstill. The coupé hits 100kph in 4.8 seconds, aided partially by the four-wheel-drive\'s 60 per cent bias to the rear wheels. Top speed is 302kph. Through fast, sweeping corners it\'s well planted, and under the right circumstances it feels just a little bit alive. It can\'t hide its chubbiness through tighter corners, where the suspension rolls noticeably even when turned up to its sportiest, but the coupé is a compelling drive all the same. The steering in the GTC is calibrated differently because of minor geometry changes on the chassis, but the end result is that it\'s too light to feel quite right. The noise from the four exhausts, visually linked into pairs with open figure-of-eight shapes, is fantastic. It\'s a deep bass thrum with vague overtones of old propeller-engined fighter planes. The company has a good bit of heritage in the aviation industry and by making one exhaust deliberately longer than the other the engineers have created an off-beat burble that\'s rich, satisfying and unique. Speaking of which, the interior is customisable to taste. The highest quality leather and wood available is standard, but customers will have options on the finish of the gear lever, the materials used to upgrade the basic plastic steering column-mounted paddles and the stitching in the trim — plus just about anything else. If you want it, Bentley can do it. The seats balance sporting support and cruising luxury with aplomb. Sometimes more lateral bracing would be welcome, but only on very twisty roads. In its most comfortable setting, the suspension handles even horrendously surfaced roads very respectably. Doubly so considering the 20in alloy wheels and low-profile tyres. With its starting point as a 6.0-litre W12 engine, Bentley perhaps had an easier task than some on the face of it to downsize and improve efficiency. But by carefully choosing technologies to fit and complement the Continental GT, the result is a very credible and very satisfying new way to drive a Bentley. From gulfnews