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ZF 8-speed cuts fuel use in new BMW 4 series

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ZF Friedrichshafen supplies the new BMW 4 series with its optional eight-speed automatic transmission.

The German supplier says the transmission can help reduce fuel consumption by up to 6 percent when compared with the previous-generation six-speed gearbox it has fit in BMW models.

ZF says the eight-speed transmission helps the 4 series accelerate faster without any negative effect on efficiency. It does this because the transmission has higher overall gear ratios and the shorter steps between the gears.

ZF engineers also say that having two more gears increases overall gear ratio, which eliminates the problem of excessive speed and torque loading on individual gears. This reduces wear and improves reliability.

The friction plates for the eight-speed automatic are supplied by BorgWarner, which established a relationship with ZF in 2009 to supply low-friction materials and clutch plates for its partner’s transmission.

The new BMW 4 series, which is available as a coupe or convertible, replaces the 3-series coupe and convertible variants.

BMW debuted the production 4-series coupe at the 2013 Frankfurt auto show. The 4 series is built at BMW’s German plants in Munich, Regensburg and Dingolfing using the L7 platform.

Output of the 4 series is forecast to peak at about 115,000 units this year with more than 70,000 of that volume expected to come from the Munich plant, according to IHS Automotive data.

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