DETROIT -- The failure of General Motors' continuously variable transmission, or CVT, is a rare and costly misfire for GM's hard-charging Powertrain division.
GM said it will end production of CVTs at the end of the 2005 model year after only three years in production.
The CVTs are built at the Fiat-GM Powertrain plant in Szentgotthard, Hungary.
A four-speed automatic will replace the CVT on the Opel Astra and on the US-market Saturn Ion coupe for the 2005 model year. Those cars also will be available with a five-speed manual. The CVT will be available in just one model in 2005, the Saturn Vue with all-wheel drive.
In 2006, GM will replace the four-speed automatic with a six-speed automatic.
GM has decided to reduce the number of transmissions it uses, said Tom Stephens, GM group vice president for global powertrain. Stephens said the new six-speed automatic would offer the same or better fuel economy over the outgoing CVT. And it will deliver better performance.
A CVT uses two sliding pulleys connected by a steel belt or chain to drive the wheels. The transmission is mostly suited to small displacement, low-torque cars. CVTs deliver fuel economy gains of about 10 percent over a four-speed automatic.
But CVT technology can be fragile.
Not only was GM's CVT late to market, but assembly glitches pushed the automaker to halt production for three months this year. When production resumed in March, GM offered the CVT with an extended warranty.
CVTs are used successfully by other manufacturers. Nissan, Mini, Audi and Honda offer vehicles with CVTs. Ford Motor Co. has launched an American-made CVT in European versions of the Focus, and the company plans extensive use of the gearbox in the Five Hundred, Freestyle and Montego.