No bolt is being left untouched as carmakers in both the U.S. and Europe strive to develop cleaner and more fuel-efficient vehicles. Everything from weight-saving measures to aerodynamic tweaks and even downsized engines are being investigated in the hope that engineers can come up with fuel economy improvements. One area that has the potential for some of the biggest gains is gearbox technology.

In its quest for improved fuel economy, Ford has adopted a strategy of replacing its aging transmission designs with more efficient ones. The Blue Oval plans to add new smooth-shifting six-speed ‘boxes to more than half of its North American product lineup, including the new 2009 Ford F-150.

Later this year, Ford will begin producing a new fuel-saving, FWD six-speed transmission for use first in the 2009 Ford Escape and Mercury Mariner, which goes on sale this summer. The new transmissions deliver 4 to 6% improvements in fuel efficiency on average compared with typical four- and five-speed gearboxes. Ford’s design features a higher than normal top gear for fuel-efficient cruising.

Beyond the new automatics, Ford will also add its dual-clutch Powershift transmission to a number of North American models with the first cars to be equipped with the fuel-saving gearbox due next year. Powershift has already shown to improve fuel-economy by 10% in the European Focus range and similar savings are expected for American models.