The big shift is on at Ford Motor Company, as the automaker plans to more than double the number — to 1.4 million — of fuel-efficient, 6-speed automatic transmissions in its North American cars and trucks by the end of 2009. The advanced transmissions provide customers 4 to 6 percent improved fuel economy compared with typical 4- and 5-speed gearboxes, as well as better acceleration and a quieter and more refined driving experience. “Advanced six-speed automatic transmissions are an important element in our sustainability strategy to improve fuel economy for our customers and reduce greenhouse gas emissions by 30 percent in our new vehicles by 2020,” said Barb Samardzich, vice president, Ford North America powertrain operations. “They also deliver improved acceleration and smoother shifting, all at a great value for consumers.” By the end of 2012, 98 percent of Ford’s North American automatic transmissions will be advanced 6-speed gearboxes. Ford’s newest 6-speed is the 6F35, which debuts in the 2009 Ford Escape and Mercury Mariner sport-utility crossover vehicles and replaces the current 4-speed. It also will be used in the 2009 Mazda Tribute, as well as two other vehicles early next year. Key to the new 6-speed transmissions is increased gear span compared with 4- and 5-speeds. This allows vehicle powertrains to operate at a more optimum level, depending on the particular driving situation.