ZF's automatic transmission customers apparently think six speeds are enough. Fourteen months after announcing that it was ready to take orders for its newly developed seven-speed automatic, ZF is still waiting for its first buyer.
Part of the problem is that moving from six to seven gears improves fuel economy by less than 1 percent. That is considerably less than the gain in moving from five speeds to six.
There is "no big advantage" to the seven-speed automatic ZF developed compared with its six-speed automatic, says Gerhard Wagner, group vice president of the car transmission division at ZF Friedrichshafen AG in Saarbrucken, Germany.
DaimlerChrysler AG is the only automaker offering a seven-speed automatic, available on certain Mercedes-Benz E-class and S-class models.
While orders for ZF's seven-speed automatic have yet to materialize, its six-speed automatic sales continue to climb, with a projection of 900,000 units in 2006. This year, ZF expects to produce about 500,000 six-speed automatics, up from 250,000 in 2003, the company says.
That transmission was introduced in 2001 on the BMW 7 series. Today, six-speed automatic transmission variants are offered on a wide range of vehicles, including the Aston Martin DB9, Rolls-Royce Phantom, Land Rover Discovery and BMW 1 series.
Wagner says automaker demand for fuel economy improvements is pushing demand for its six-speed automatic.
Generally speaking, there is a 3 percent to 4 percent fuel economy increase when an automaker switches from a four-speed automatic to a five-speed, Wagner says. Fuel economy increases about 5 percent if an automaker switches from a five-speed automatic to a six.
ZF makes a distinction between its automatic and manual/automatic transmissions. The Shifttronic manual/automatic, available as a seven-speed, debuted on the 2005 BMW M5. That transmission is engineered for high-performance vehicles.
ZF had announced at the 2003 Frankfurt auto show that it had developed a seven-speed automatic transmission. But, Wagner says, "We will decide to go into production only if we have commitment from customers."
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