SANTA BARBARA, CA – After four years of collaboration, Ford Motor Co. and General Motors Corp. this fall are launching vehicles using an all-new 6-speed automatic transmission jointly developed by the two auto makers.

The ’07 Saturn Aura, now on sale, is the first GM vehicle to use the transmission.

The ’07 Saturn Outlook cross/utility vehicle also uses the new 6-speed automatic, with many other future GM models to follow, thanks to the transmission’s adaptability for either front-wheel-drive or all-wheel-drive configurations.

Ford’s Edge CUV and its Lincoln MKX will be the first Ford-built vehicles to be equipped with the 6-speed automatic when they are introduced late this year.

However, the partnership will not end with the production debuts for the transmission. “We expect the project to last for a long time,” says Bob Vargo, GM’s assistant chief engineer on the development team.

Both Ford and GM team members interacted very professionally, Vargo says. The teams will continue to meet through the launch and post-launch periods.

“We checked our egos at the door,” Vargo says. “‘Get mad and get over it’,” he says he told his team. “There was very little disagreement or fighting on the engineering side.”

The payoff for both auto makers was about a 40% savings in development costs.

“We also saved from the resource-utilization standpoint,” says Ram Krishnaswami, manager of the Ford S50/55 transmission group, who also endorses Vargo’s assessment of the two companies’ cooperation.

“There were a couple of differences that we talked through,” he says. “Then we made some compromises.”

The most significant difference in the production transmission is that the auto makers use unique hydraulic-control modules.

Ford’s transmission, for example, doesn’t have an independent transmission controller. “That provides a better value to the customer,” Krishnaswami says.

The combined teams “gave us the best of both worlds,” he says. The amount of work put in by the respective teams was about equal in many respects, but GM got a head start on designing the architecture. “We joined later,” Krishnaswami says.

There are other differences in the respective transmission designs because each auto maker obviously couples the transmission to its own engines.

GM has a unique distance from the centerline of the engine crankshaft to the centerline of the front axle. The same dimension for Ford is longer in order to accommodate its engine.

“There will always be adaptation difference,” Vargo says.

Krishnaswami estimates from a hardware standpoint, the transmissions are about 85% identical. He says Ford also differentiates the way the transmission shifts.

“We wanted a high level of customer satisfaction,” he says. “The transmission provides smooth, seamless shifting and lightning-fast downshifts.”

Ford uses a unique calibration to make the transmission shift more responsively on hilly terrain and through switchbacks, he adds.

GM purchases its control module, Vargo says. It also outsources major castings but machines them in-house.

“We manufacture all our own gears,” he adds. “The gears (for each auto maker’s variant) are not identical, but they’re very close.”

Vargo says the new co-developed 6-speed automatic transmission “can compete with anything else out there.”

Up-level Saturn Aura XR models, equipped with a 3.6L DOHC V-6 rated at 252 hp and 251 lb.-ft. (340 Nm) of torque mate with the Hydra-Matic 6T70 6-speed automatic.

The 6T70 – GM’s first application of a FWD 6-speed automatic – provides the added benefit of Driver Shift Control, which enables the driver to manually shift through gears via steering-wheel-positioned paddles.

Vargo claims the 6-speed provides a definite improvement over existing GM 4-speed automatics in fuel economy, up to 4%. However, he doesn’t believe GM needs to evolve to 7- and 8-speed automatic transmissions, as some auto makers are doing.

“I’m not sure we know how to make a 7- or 8-speed without adding components,” he says. “I believe our 6-speed is the most elegant design for the consumer. As you add speeds, there’s a law of diminishing returns.”

He also says the new 6-speed costs about the same as a 4-speed automatic.

Vargo says the transmission’s development team also targeted high durability.

“Our transmission just keeps going and going (on the dynamometer) just like the Eveready battery,” he says. “We’re shooting for a 200,000-mile (322,000-km) life for the transmission.”

Ford and GM are contractually obligated to share changes they make down the road, as well as cost-reduction results obtained from new hardware.

GM is manufacturing the transmission at a plant in Warren, MI. “We’re producing about 1,500 units a day,” Vargo says.

Ford currently is ramping up production at its Sterling Heights, MI, plant.

Vargo says GM has not developed a 6-speed automatic before now because previous designs required too many added components.

“This 6-speed has the same number of components as the 4-speed GM (automatic) transmission,” he says.

The joint-development agreement also stipulates Ford and GM can sell the transmission to other companies if they desire. “Some companies have expressed interest,” Vargo says.

Ford and GM are the fiercest of rivals in the marketplace, but their respective transmission development teams have formed close relationships and frequently are in touch.

For the past four years, they have enjoyed two annual get-togethers: a golf tournament and a bowling tournament.

However, neither Vargo nor Krishnaswami can explain why GM engineers always prevail at golf and the Ford engineers dominate in bowling.