General Motors' powertrain division is rolling out a variety of fuel-saving, high-tech engines; hybrid powertrains; and six-speed automatic transmissions.

Because of high costs, GM does not plan to add diesels to passenger cars and light trucks before at least 2010.

Here's a look at GM's strategy:

Hybrids: GM plans a dozen hybrids by the end of the decade. But only eight models have been named thus far. GM's hybrid plans are much like its engine strategy. Some hybrid powertrains will be high-value and some high-feature.

GM's first real hybrid, the Saturn Vue Greenline, is on the way to dealerships. The Vue Greenline, a mild hybrid, boosts fuel economy by 20 percent and gives the compact SUV a best-in-class highway figure of 32 mpg, GM says. The company will market the vehicle as the first affordable hybrid. The option is priced at only $1,995, putting the cost of the vehicle in the low $20,000s.

The next hybrids in the pipeline are the Saturn Aura in the first half of the 2007 model year, followed by the Chevrolet Malibu later next year. Both cars use the Greenline's belt-alternator hybrid system. GM says it can install this system in any vehicle that uses the Ecotech four-cylinder engine.

Next, GM plans to roll out its first full hybrids in the Chevrolet Tahoe, GMC Yukon and Cadillac Escalade. The 2008 Tahoe hybrid arrives in late 2007, followed by the Yukon. In 2008 comes the Escalade, which may be a 2009 model. Those vehicles use a rear-wheel-drive transmission with two electric motors.

GM calls the transmission the Two-Mode, and it is being developed with BMW and DaimlerChrysler. The Two-Mode is also slated for use in GM's crew-cab pickups around 2008.

GM is likely to round out its planned dozen hybrids by expanding the Two Mode into other truck-based vehicles.

The automaker is testing a diesel-electric hybrid powertrain for the Opel and Saab brands. A GM insider says costs could be brought under control, and production is possible.

Diesels: Unlike Ford and the Chrysler group, GM has no plans to install fuel-saving diesel engines in North American cars or light trucks. GM has built and tested a V-6 version of the Duramax diesel V-8 but shelved the engine two years ago. The barriers were technical challenges and the cost of an emissions system that meets upcoming air quality regulations.

"We think we can do it, but it is going to mean that light-duty diesels are going to have several thousand dollars worth of additional control and after-treatment technology," GM Vice Chairman Bob Lutz said recently.

One possibility: GM could use Saab to break into passenger-car diesels in the United States, as Ford Motor Co. might with its Volvo brand.

GM's lone diesel for the United States, the Duramax V-8 used in heavy-duty pickups, is being revamped for 2007. The engine, due in the first quarter of 2007, may grow in size and power.

Production at the Moraine, Ohio, engine plant is limited to about 180,000 engines per year. GM does not plan to add capacity, even though it could sell many more, said Tom Stephens, GM Powertrain Group vice president.

Gasoline engines: Look for GM to boost its corporate average fuel economy numbers and lower emissions by equipping more gasoline engines, both push-rod and overhead-cam, with high-tech features. That includes such things as direct fuel injection and variable valve timing. Turbochargers also could gain wider use as GM boosts fuel economy by shrinking engines.

The optional 260-hp, 2.0-liter turbocharged, direct-injected four-cylinder in the Pontiac Solstice GXP and Saturn Sky Redline could signal GM's future strategy for ultrapowerful small-displacement engines. Meanwhile, GM in 2007 plans to expand the availability of its fuel-saving cylinder cutoff technology from V-8 truck engines to the 3.9-liter V-6 in the Chevrolet Malibu.

GM plans to offer 14 vehicles in 2007 that can run on E85 ethanol. It is the only automaker certified to sell E85 vehicles in all 50 states.

Transmissions: GM's plans to boost fuel economy also include using a greater number of six-speed automatic transmissions. In July, production of a new front-wheel-drive six-speed automatic started in a Detroit area factory. GM expects a 4 percent fuel economy gain from the six-speed over the four-speed it replaces.

GM plans to use the gearbox in numerous models, including the Pontiac G6, Saturn Aura and GMC Acadia. The gearbox also can be used in all-wheel-drive applications.

GM is also moving to six-speed automatics in rear- and all-wheel drive vehicles such as the Cadillac SRX and STS.