Bentley promises major emissions savings with new Continental GT

  • 23-Sep-2010 09:37 EDT
Bentley9-10 CGT Front.jpg

Superformed aluminum front fenders are fitted to the new Bentley Continental GT. 

Bentley’s new Continental GT may look very similar to the previous generation, but Engineering Director Dr. Ulrich Eichhorn quantifies the difference between the two at 70%. And Bentley Chairman and Chief Executive, Dr. Franz-Josef Paefgen, said: “It drives like a supercar, but without the usual sacrifices in ride or practicality.”

Initially available with an uprated W12 engine, the car will also be offered from late 2011 with a new 4.0-L V8 gasoline engine, developed together with Audi, that should see a very significant reduction over the current GT’s emissions. It is likely that the engine will drive through a ZF eight-speed auto transmission to aid both performance and fuel consumption/emissions.

Two years ago Eichhorn said that a target of 40% in emissions reduction was a reality for the future and the direct-injection V8 will pave the way to achieving that. The engine, with a 0.2-L smaller capacity than Audi’s established gasoline V8, is likely to be turbocharged (or supercharged), to make it a suitable alternative to (or successor of) the big twin-turbo 6.0-L W12, now producing 423 kW (567 hp) and 700 N·m (516 lb·ft).

It is seven years since the first Continental GT appeared and some 23,000 have been built to date, a figure that the ultralow-volume Bentley company of even a couple of decades ago, would have found unthinkable. With the latest car, Bentley is clearly aiming to maintain or expand its sales targets.

The new GT has identical external dimensions to the old model save for its width, and track is increased by 41 and 48 mm (1.6 and 1.9 in) at the front and rear, respectively.

All panels of the latest GT are changed, to give the car a crisper profile, with some much sharper radii; Design Director Dirk van Braeckel wanted to enhance the car’s character as a sporty 2+2 grand tourer. The changes may be significant in engineering and manufacturing terms, but they are aesthetically subtle and perhaps indicate that the car’s signature is set to be “timeless,” with only mild evolution, much as that of the Porsche 911.

Aerodynamic efficiency has been improved, with extensive underbody refinements including wheel-arch and exhaust system aids to contribute to a Cd figure of 0.33. Bentley has focused on wind tunnel work also to lower lift at the front and rear axles. The radiator is more upright, and the car has LED daytime running lights. LED lights are also used at the rear, wrapping around into the fenders.

Wheels are 20-in alloys as standard, with a 21-in upgrade available.

Mechanical changes include a torque split change in the all-wheel drive system (with Torsen differential) to a 40:60 front:rear bias in regular driving (as used by the Continental Supersports) to provide sportier handling. The torque bias varies according to adhesion requirements. The ESC (electronic stability control) has also been uprated to give the chassis greater capability and safety.

But the most interesting mechanical development—the new 4.0-L V8—remains shrouded in commercial semi-secrecy. Although no specific details have been released by Bentley/Audi, it is claimed to have a class-leading CO2 emissions-to-power ratio.

It was in 2008 that Bentley announced its future environmental program targets, including a 15% improvement in overall powertrain efficiency and the adoption across the range by 2012 of its FlexFuel capability.

Bentley remains fond of quoting well-to-wheel (“the measurement of CO2 released by a fuel from its production (well) through to its combustion or deployment (wheel)) figures, which are not the market norm. Using those, the company stated that the 2012 range average will produce potential reductions of CO2 of some 70%.

So far, Bentley has given no firm indication of the possible introduction of a production diesel powertrain, which it probably deems inappropriate for a very high level sedan.

For the new W12 Continental GT, the company has stated that, to ensure the power and torque generated remain constant regardless of fuel burned, an advanced fuel quality sensor is used, to continuously monitor the ratio of the fuels used and guide the ECU (engine control unit) to adjust the power unit’s timing to provide the level of power delivery smoothness that is a central element of the marque.

The W12’s upgrades also include low friction, lightweight components, and further optimization of the unit’s twin, low inertia turbochargers.

Weight savings against the outgoing model totals 65 kg (143 lb), achieved via reductions across the car’s systems, from components to seat design. Together with the increase in engine power and torque, a 6% improvement in power:weight ratio has been achieved. Performance figures now include a 0-100 km/h (0-62 mph) time of 4.6 s and top speed of 318 km/h (198 mph).

The new car’s six-speed ZF transmission features Quickshift, halving shift times to a best of 200 ms, and the gearbox can achieve double downshifts. The planetary set of the transmission has been strengthened. Positive torque during downshifts is provided via engine and gearbox electronic controller interaction for extra throttle and fuel injection on the overrun, replicating throttle blips for rev matching. For upward gear changes, fuel and ignition are cut momentarily to reduce torque for faster shifts.

Significant bodyshell changes include the use of aluminum superforming for the front fenders and trunk lid. The material is heated to almost 500ºF (260°C) and then shaped by air pressure. Because a single sheet of aluminum is used, neither seams nor welding are required. The hood and doors are also aluminum.

The interior has also been changed, with a dashboard finished in premium hide and “Cobra” design seats. Bentley has moved to an 8-in touch-screen 30-GB infotainment system, including Google Maps compatibility according to market. The GT’s audio systems have the latest high-frequency BMR (balance mode radiator) speakers. An 11-speaker Naim system uses Disc Dimensions digital signal processing. Claimed as an industry “first,” it is described as providing a virtual “sound field” independent of speaker layout to deliver “concert hall” quality sound for each seat occupant.

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