BMW has announced the launch of a new engine to the BMW 6 Series range at the same time as the model line-up has been revised. The BMW 635d opens up a new sector of the market for BMW by mating the acclaimed twin-turbocharged diesel to the marque’s flagship Grand Tourer. The launch of the BMW 635d coincides with the introduction of fuel saving and emissions-cutting EfficientDynamics technology to the rest of the 6 Series range to improve performance. The model has also been given a subtle restyling to mark the technological changes.

With the world’s most powerful production six-cylinder diesel under the bonnet the BMW 635d Coupé and Convertible are unique in their segments. No other competitor can offer such frugal motoring in a Grand Tourer while still satisfying the demands of sophisticated buyers who insist on the best in performance and refinement.

Powered by a twin-turbocharged 2,993cc engine with an all aluminium crankcase and third generation common rail fuel injection system, the 635d comes with an output of 286hp and 580Nm of torque. These impressive performance figures have been made possible by the unique way the twin turbochargers work. A smaller turbocharger provides near instantaneous response for swift initial acceleration before a larger turbocharger comes in mid-range to provide additional thrust through to the redline. With peak torque available from just 1,750rpm a seamless wave of smooth acceleration is provided for the driver.

The result of this engineering excellence sees the BMW 635d Coupé record a zero to 62mph time of 6.3 seconds while the Convertible achieves this in 6.6 seconds. Both have top speeds electronically-limited to 155mph. However, the Coupé still achieves 40.9mpg on the combined cycle and a CO2 emissions figure of 183g/km, while the Convertible retains near identical figures recording 39.2mpg and 190g/km.

Aiding the BMW 635d’s performance is the introduction of EfficientDynamics technology. For the first time in the 6 Series, the range comes with Brake Energy Regeneration and the implementation of various needs-only operations of ancillary units. For example, the air-conditioning compressor can be decoupled from the drivetrain to prevent unnecessary drag on the engine and lower viscosity fluids are used in key components to reduce friction. An optimum gearshift indicator is fitted to advise on economical motoring, while active flaps located behind the kidney grille can close off to improve aerodynamic flow and reduce drag. These measures all add up to a BMW 635d that records lower fuel consumption and emissions figures than would previously have been possible.

The BMW 635d is joined in the range by the 630i and 650i, offered in both Coupé and Convertible bodystyles. The six-cylinder magnesium and aluminium engine in the 272hp 630i now features new lean burn technology in the guise of high precision direct injection and double-VANOS variable valve technology. With its piezo crystal injectors for optimium fuel atomisation, the new style of induction makes for a subsequent near-complete fuel vapour burn and the best in engine efficiency.

High precision direct injection technology combined with the introduction of EfficientDynamics sees the 630i Coupé record a 4.4mpg improvement up to 35.8mpg in combined fuel consumption compared to the previous model. CO2 emissions also drop from 216g/km to 188g/km. BMW 630i Coupés fitted with automatic transmissions post even better performance figures with combined fuel consumption rising from 29.7mpg to 36.7mpg and emissions falling from 238g/km to 184g/km. The 630i Convertible attains a combined fuel consumption figure of 34.0mpg compared to 29.4mpg, while CO2 emissions drops from 229g/km to 198g/km.

The BMW 650i Coupé and Convertible models crown the range and are powered by a 4,799cc V8 engine providing an output of 367hp. The 650i with its aluminium engine and double-VANOS and VALVETRONIC variable valve technology is capable of a zero to 62mph time of 5.1 seconds in the Coupé and 5.5 seconds in the Convertible. Again EfficientDynamics technology plays a part in both 650i models to achieve improved economy and emissions figures. For the 650i Coupé consumption on the combined cycle improves by 2 per cent to 24.1mpg, while emissions drop by 2 per cent to 279g/km. The 650i Convertible also achieves better performance recording 22.4mpg, up 7 per cent. CO2 emissions are cut from 310g/km to 299g/km.

The 630i and 650i comes as standard with a six-speed manual gearbox, while the 635d is offered with a new six-speed sports automatic transmission. This gearbox features a new torque converter with enhanced software and a two-stage damper to reduce vibrations. The enhanced transmission specification means power-wasting slip in the converter is largely eliminated and with the improved software results in gearshift times that are smoother and 50 per cent quicker.

To highlight the engineering changes introduced on the BMW 6 Series, the model has been subject to some subtle design enhancements. The exterior of the car features a revised headlight arrangement featuring LED technology and clear lenses, and a new style of front valance. The vertical struts on the front spoiler have been repositioned to accommodate a different shape of air intake for the car and the kidney grille is larger compared to the outgoing model.

At the rear, the lower reflectors have been optically enhanced as part of a redesigned rear bumper to emphasise the wide track, while a third high level brake light now sits on the boot lid lip for improved safety. The introduction of new alloy wheel design in 17-, 18- and 19-inch sizes completes the exterior changes.

Inside, and customers of 6 Series Convertible models can specify SunReflective Technology leather. This bespoke upholstery has embedded pigments in the leather that reflect infra-red radiation in the sunlight and can reduce leather temperature by up to 20 degrees centigrade.

The revised 6 Series now features an infotainment system that includes eight ‘Favourite’ buttons. BMWs have featured popular programmable buttons on the steering wheel for a number of years and the 6 Series comes with a small bank of programmable buttons for added convenience on the centre console. These can be customised and used as shortcuts to the most frequently visited parts of the iDrive system such as navigation destinations or radio stations.

BMW is at the forefront of automotive safety technology and Active Headrests appear on the 6 Series for the first time. Standard fit on cars, the system has been introduced to prevent occupants from whiplash injuries in rear end accidents. When the airbags’ central control unit registers a rear end collision pyrotechnics fire to release two springs in the head rests. These then rapidly push the front of the restraint forward by 6cms and upwards by 4cms, reducing risk to the driver and front seat passenger of serious neck injury.

The BMW 6 Series is the first BMW to get Active Headrests, but the technology will appear on other models in the BMW product portfolio shortly.

The new BMW 6 Series goes on sale in the UK in October.