BMW claims the ZF eight-speed automatic can compete with dual-clutch transmissions on shift timesEnlarge Photo
Speaking with Automotive News, BMW development chief Klaus Draeger said the luxury carmaker plans to focus on automatic transmissions instead of dual-clutch units for its high-volume models.
“The eight-speed automatic that we developed with ZF can compete with dual-clutch transmissions on shifting times, but it’s lighter and more efficient and has cost advantages,” he revealed. “The incompatibility with high engine-speed designs is a disadvantage, however.”
Draeger went on to explain that dual-clutch transmissions are complex, expensive and heavy, especially for cars with longitudinally mounted engines and RWD.
ZF’s new eight-speed auto, meanwhile, has been designed for both RWD and AWD cars and will appear in several BMW and Audi models later this year. The extra cogs have the added benefit of improved fuel economy because the gearbox can better match engine speeds with the right gear since there’s more to choose from. To further enhance fuel-economy, the new ZF gearbox will also have an engine stop-start feature.
Using BMW’s own vehicle test data, ZF has found that the transmissions achieves a fuel economy benefit of 3% for gasoline engines and 6% for diesel engines over its current six-speed auto. Both the first and second generation gearboxes will be built at ZF’s Saarbrucken plant in Germany with half of these earmarked for use in BMW vehicles.