DETROIT-Ford Motor Co. and General Motors Corp. will jointly invest $720 million in their plants to build a fuel-saving, six-speed, front-wheel drive automatic transmission.

The transmission will be built separately at GM's Warren transmission plant and Ford's Van Dyke and Sharonville transmission plants.

Ford will build major components, manufacture the gears and assemble the transmission. GM will build major components and assemble GM six-speeds.

The transmission is expected to offer up to 4 percent improvement in fuel economy over traditional four-speed automatic transmissions available in current front-wheel drive cars. On the economic side, about 900 jobs will be retained to work on the transmission.

Production is scheduled to begin at both companies in 2006.