Though they are expensive and complex to engineer and build, automatic transmissions with five, six and even seven speeds will help automakers improve fuel economy and lower emissions.

The challenge engineers face is reigning in costs.

The same applies to one-speed continuously variable transmissions. But CVTs still have a spotty reliability record and have yet to reach high-volume production.

For years, most automatics have had either three or four speeds. There are a few five- and six-speed automatics on the U.S. market, most of them in luxury cars. Because the electronic controls that link the engine and transmission have been improved so much, automatics with five or more speeds can be programmed to shift gears at precisely the right time. That improves acceleration, smoothness and fuel economy while reducing harmful emissions.

Forget 5

"Six-speed automatics will soon rule the industry," predicts Lindsay Brooke, powertrain analyst with CSM Worldwide, a forecasting service in Southfield, Mich. "With a few exceptions, automakers are leap-frogging five-speeds and going directly to six-speeds."

ZF Friedrichshafen AG, a major transmission supplier in Germany, has seen an increase in the number of six-speed automatics that it sells. ZF produced about 250,000 of the units in 2003. This year, sales are expected to be 900,000 units.

Saving money is the main reason rivals General Motors and Ford Motor Co. formed a partnership in 2002 to produce a six-speed automatic for front-wheel-drive vehicles.

The $720 million GM-Ford project underscores how much can be saved on a transmission when high volumes are produced. Ford last year said the installation rate for six-speed transmissions in Ford products could be 50 percent by 2015.

As many a 1 million units can be produced each year in three U.S. plants. GM and Ford estimate the jointly developed transmission will save about $1,000 per unit once production is cranking. They also expect to book a 4 percent gain in fuel economy.

On paper, the GM-Ford six-speed transmission looks technically impressive. The transmission will give both companies an advantage over most competitors. But Thomas Stephens, GM Powertrain group vice president, says most buyers won't care how many gears the transmission has.

"The biggest part of the general customer base wants reasonably good fuel economy in a vehicle that never, ever lets them down," Stephens says.

"What they care is about is when they go to start that vehicle that it starts every time," he says.

"And when they go to drive away that it is smooth and quiet. When they go to pass someone on a two-lane road or merge onto the expressway that they feel safe. Technology-wise, whatever I have to do to make that happen is OK with them. But you better do it at the lowest possible cost and price."

The Chrysler group has not announced plans to compete with GM and Ford with its own six-speed transmission. Bob Lee, the Chrysler group's powertrain product engineering vice president, would not talk specifically about any new transmissions on which his company is working.



Lee says Chrysler has placed a high priority not only on developing new transmissions but also in integrating them to the rest of the vehicle.

"Transmissions rank very high, more highly than I can tell you about," he says. "We've got more driveline programs going on now than we've ever had in our history. It's really a systems issue that includes transfer cases and vehicle configurations."

CVT future isn't clear

The future of CVTs in North America is less clear.

GM failed with the CVT in the Saturn Vue SUV, pulling the problem-plagued gearbox from production after about 86,000 were built.

The CVT in several new Ford products, such as the Ford Five Hundred and Mercury Montego, has had a few minor teething problems. Engineers have wrestled with noise and production is running slower than Ford planned. And Ford has been trying to reduce the costs of the transmission, which was developed with ZF.

But Honda, Nissan and Audi vehicles equipped with CVTs are selling well, though not in high volumes.

GM is finished with CVTs. Stephens said that five- and six-speed transmissions can be used with a greater number of engines and deliver the same or better fuel economy.

CVTs are limited to smaller engines because they can't handle high horsepower.

Ford is committed to CVTs, at least in the short term, says Dave Szczupak, Ford's powertrain group vice president.

"I don't think any of us has decided which technology will win long term," he says. "Maybe they can co-exist. Clearly, what customers are saying is give us smooth-shifting transmissions with a good ratio range. The six-speed and the CVT do that. I don't think one or the other technology will win. I think they both have a place."