updated 5/7/2008 5:52:50 PM ET 2008-05-07T21:52:50

Ford Motor Co. said Wednesday it plans to double the number of six-speed automatic transmissions in its models by the end of next year, increasing fuel efficiency to the point where it's equal to or better than manual gearboxes.

The company also said that 98 percent of its North American transmissions will be six speeds by the end of 2012 as it moves to meet increasing government fuel economy standards.

The computer-controlled transmissions, built at a revamped factory in Sterling Heights, give drivers a 4 percent to 6 percent gas mileage boost compared with the four- and five-speed models now in widespread use in Ford's front-wheel-drive vehicles.

Because the computer calculates when to shift gears so the engine runs at peak efficiency, they can rival the mileage of lighter manual gearboxes, said Ram Krisnaswami, a Ford powertrain engineering manager.

"Some of the efficiencies within the transmission, probably the manual will score better than the automatic. But then your driving patterns, and being able to operate in the sweet spot, let the computer do it, then the automatic scores," he said. "As we improve the internal efficiency of the transmission, the automatics approach a well-driven manual by an expert."

The new transmissions allow the car to achieve higher speeds with fewer engine revolutions per minute, making it more efficient, Ford said.

The Dearborn-based automaker says its 6F35 six-speed transmissions will debut in the 2009-model Ford Escape and Mercury Mariner crossover vehicles, which now have four-speed automatic transmissions. They also will go into the 2009 Mazda Tribute and two other vehicles early next year, Ford said.

The new transmissions will also be low-maintenance, with no need to replace the fluid in the gearboxes for the life of the vehicle, Ford said.

Ford Vice President Barb Samardzich, head of the company's North American transmission operations, said the new transmissions are key to Ford's planned 30 percent cut in vehicle greenhouse gas emissions by 2020.

"They also deliver improved acceleration and smoother shifting, all at a great value for consumers," she said in a statement.

Congress passed a law last year that requires new cars and trucks to meet a fleet average of 35 mpg by 2020, a 40 percent increase from the current average requirement of 25 mpg.

Ford said it plans to sell 1.4 million six-speed vehicles in North America by the end of next year. In addition to the 6F35 transmissions, Ford also makes another six-speed transmission that was jointly developed with General Motors Corp.

GM recently introduced the six-speed in a four-cylinder version of the Chevrolet Malibu, boosting the midsize car's highway miles per gallon from 30 to 32. GM said last month that the new powertrain would debut immediately in the high-end Malibu LTZ and next year in two lower-priced Malibu models.

Ford said it invested $658 million in Sterling Heights and at factories in Livonia and Sharonville, Ohio, to make the transmissions.

Other automakers are coming out with their own high-tech transmissions with six or more speeds. Hyundai Motor Co. plans a six-speed in its new Genesis luxury car, while Daimler AG's Mercedes brand has a seven-speed and Toyota Motor Corp.'s Lexus luxury brand has an eight-speed automatic.

Krisnaswami said six speeds are very efficient and cost effective, and automakers have to weigh efficiency gains against added costs, weight and shifting that come with more gears.

Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.


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