General Motors will produce a 7.5-liter V-12 engine to be used in future Cadillacs and will launch a family of overhead-cam, high output V-6 engines. GM also is revamping its pushrod V-6 engine family to include displacements of up to 3.9 liters and equipping the engines with fuel-saving cylinder deactivation technology, the automaker said Friday, Oct. 4, during a press event at its proving grounds in Milford, MI. Another addition to the automaker's portfolio is a six-speed, rear-wheel-drive automatic transmission that will go into production in 2005.The new overhead-cam V-6 engine family will have displacements ranging from 2.8 liters to 3.8 liters, aluminum blocks and cylinder heads and four valves per cylinder. GM said the first engine from the family will be a 3.6-liter V-6 that makes 255 hp and 250 pounds-feet of torque through technologies such as variable valve timing. It did not disclose when the engine will be introduced or in which vehicle. The first of the revamped pushrod V-6 engines, using cylinder deactivation technology, will be a 3.5-liter unit in the redesigned Chevrolet Malibu, which goes on sale next year. The engine will run on only three cylinders when power demands are light, such as cruising at highway speeds.