Six-speed automatic transmissions are expected to hold more than 60% of the North American light vehicle market by 2012 compared with less than 5% of transmissions built in the region at present, according to CSM Worldwide's latest powertrain production forecast.

"The reason for the increasing production of six-speed A/Ts is quite simple: consumers want them. What's interesting, however, is they may not know they want them," CSM said.

"American car buyers are looking for a number of things: better fuel economy, better ride quality, and more power. They don't necessarily know or care how these qualities get in the car, as long as they're there," said Casey Selecman, the firm's manager of North American powertrain forecasts.

"Six-speed ATs help address all of these consumer demands in one package. With few exceptions, OEMs are moving to an all six-speed-automatic fleet for North America."

At General Motors, where the shift is already taking place, more than 75% of transmissions built in North America will be six-speed automatics by 2012. Current vehicles such as the Chevrolet Corvette and GMC Yukon are now available with six-speed automatics. Ford and DaimlerChrysler will be phasing six-speeds in during the next several years, as is Toyota. Hyundai will localise transmission production of its new front-wheel drive six-speed by the end of 2008, with assembly likely to be in Alabama, near its engine and vehicle production facilities.

Conversely, four- and five-speed automatic transmissions will go from more than 90% market share in 2005 to less than 40% share in 2012.