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Friday, February 1, 2008

2008 Saab 9-4X BioPower Concept

The Saab 9-4X BioPower Concept demonstrates the potential of “rightsizing” – achieving sufficient levels of performance with a smaller, more efficient engine – by showcasing a 2.0-liter, four-cylinder turbo engine optimized for bioethanol (E85) fuel. The BioPower engine delivers 300 horsepower (221 kW) and 295 lb.-ft. (400 Nm) of torque.

With 30 years of experience in turbo technology, Saab leads the automotive industry in leveraging the performance and environmental benefits of bioethanol fuel. Its current BioPower models are the top-selling flex-fuel vehicles in Europe and the only products in this emerging segment to offer more power from E85 fuel, in conjunction with substantially reduced CO 2 emissions on a source-to-wheel basis, compared to gasoline-only operation.

With the announcement of the Saab 9-4X BioPower Concept, Saab takes a next step in the development of responsible performance by partnering BioPower technology with all-wheel drive (Saab XWD) for the first time in the crossover segment.

The lightweight, all-aluminum, four-cylinder engine is optimized for E85 fuel (85 percent bioethanol and15 percent gasoline) to give an exceptionally high specific power output of 150 horsepower per liter cylinder volume, together with an equally impressive 295 lb.-ft. (400 Nm) of torque, versus 245 horsepower (180 kW) and 260 lb.-ft. (353 Nm) on gasoline).

E85 has a higher octane rating (104 RON) than gasoline, making it more resistant to harmful pre-detonation, or “knocking,” when the fuel/air mixture is compressed in the cylinder. To fully exploit this advantage, the engine has a raised compression ratio, 10.5:1, instead of 9.2:1 for a gasoline-only application. It retains its flex-fuel capability because the Saab engine management system adjusts the ignition timing and turbo boost pressure to ensure there is no pre-detonation with gasoline.

Engine efficiency is also improved by the use of direct injection (DI) and continuously variable valve timing (VVT) on both the inlet and exhaust sides. DI delivers fuel directly into the combustion chamber, providing a more complete burn of the fuel/air mixture to give more power with reduced fuel consumption.

VVT enhances turbo response at low engine speeds, as well as contributing to an even wider spread of torque. On E85 fuel, that impressive 295 lb.-ft. ( 400 Nm) of torque is generated all the way from 2,600 to 5,100 rpm, with 85 percent available from just 2,000 rpm. While these figures may be matched by a much larger, naturally aspirated engine, the characteristic “tidal wave” of low-end torque is unique to the turbocharged power delivery.

The cutting-edge Saab XWD all-wheel-drive system, recently launched in the 9-3, is designed to optimize vehicle handling and stability. It features active management that not only splits torque delivery between the axles, but also between the rear wheels via an electronically controlled rear limited-slip differential (eLSD). This can transfer up to 40 percent of torque between the rear drive shafts, to whichever wheel has more grip. Such active drive torque management improves both cornering and stability by making the rear of the car more closely follow the direction of the front wheels.

This responsive system allows a higher level of driver involvement through positive force chassis control before any electronic stability aids are deployed.

Driving enjoyment can be further enhanced by the selection of “Sport” or “Comfort” modes as an alternative to the vehicle’s standard chassis settings. Sport mode stiffens the action of the dampers for greater body and wheel control; sets the gearshift points of the automatic transmission at higher engine speeds for sportier driving; sends more torque to the rear axle for greater agility; increases the sensitivity of the electronic throttle; and reduces the power assistance for greater steering feel at speed.

Responsible performance also means including important safety features. In addition to a full arsenal of electronic stability and braking systems, the Saab 9-4X BioPower Concept features rollover sensing for deployment of the side curtain air bags. The front seats are also fitted with new, Generation III Saab Active Head Restraints (SAHR), including a revised head restraint movement to help reduce the risk of severe neck injury to front-seat passengers.

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