Bentley Continental Flying Spur - the world's fastest four door saloon

The Borg-Warner turbochargers are also the ideal solution for producing the flat torque curve that is a key characteristic of every Bentley engine, ensuring that the driver has instantly available performance without a hint of turbo lag or having to shift down through the gears. That mighty torque curve is constant, with no drop-off from its maximum output of 479lb ft (650Nm) at just 1600rpm.

Packaging all those systems was a remarkable challenge in itself. The astonishing compactness of the engine - it is just 653mm long - was a critical target and with such immense amounts of torque it was equally imperative to have impressive traction in any conditions. What was called for was an all-wheel drive system that could cope with the Continental Flying Spur's performance capability and consequently as short an engine as possible to allow room for the extra componentry.

"The internal packaging of the engine is amazing," says Francis Ellison, module leader, powertrain. "And that helped when it came to designing all the other elements of the car's powertrain assembly. Because of the performance requirements, we wanted the centre of gravity to remain as low as possible and this meant we couldn't have the front differential under the engine. Instead we placed it between the engine and the gearbox. You can only do that if you have a very compact engine to begin with, otherwise you would have a car with a very long nose."

With ideal positioning of the main parts of the powertrain, the Continental Flying Spur has a 56:44 weight distribution over the front and rear axles. Unlike rear-wheel drive cars with large amounts of power, which are forced to put more weight over the rear wheels to improve traction, the Bentley's all-wheel drive system means the weight balance can be biased towards the front, thereby improving both the agility and handling of the car.

"Because we have a close to ideal distribution of weight, the Continental Flying Spur has excellent initial grip and turn-in when you start cornering," says Dr Ulrich Eichhorn. "You also get very good high-speed stability and it is much easier to tune an inherently stable chassis like ours to be agile than to make a nervous one stable."

Work was not just carried out on the performance capabilities of the engine but also its acoustic properties. The Continental Flying Spur has a re-engineered exhaust system that provides greater refinement for a car that has a broader role than the coupe.

"We have added a cross-tube in the centre of the exhaust system and we have also optimised the exhaust valve system to get the right acoustic pattern," explains Cameron Paterson, head of engineering for the Continental Flying Spur. "The exhaust note in the Continental GT coupe was deliberately quite noticeable - it is a sports car after all. For the Continental Flying Spur we wanted to ensure more refinement when you are driving in a leisurely fashion but still create that unmistakeable Bentley sound when you are pressing on. With this new exhaust system we can achieve that by closing off one tailpipe at differing engine load levels."

The Continental Flying Spur's prodigious power is channelled through a six-speed automatic transmission built for Bentley by ZF. This is the same gearbox as used in the coupe but it has been recalibrated. The principle behind the reworked transmission is to give a more relaxed driving style but to retain the car's full performance when called upon. At most times the transmission will rely on the enormous torque produced by the engine to do more of the propulsion, thereby avoiding unnecessary downshifting and allowing the driver to enjoy the tremendous pulling power of the engine as well as giving a smoother driving experience.

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