Saturn Corp.'s forthcoming sport-utility will feature a continuously variable transmission built by General Motors' Powertrain division.
According to sources at GM and its suppliers, four-cylinder versions of the Saturn sport-utility due for the 2002 model year will feature a CVT, a type of transmission that can vary its speed ratios infinitely within a range. The decision to equip the Saturn with a CVT polishes up GM's engine technology credentials and gives a major boost to a fuel-saving technology that until now has made little headway in North America.
The Saturn sport-utility is known internally as GMX315. It will be built at the company's Spring Hill, Tenn., plant. A Saturn spokesman declined to comment.
The vehicle design is a grab bag of existing car platforms and new parts. It will be about the size of the Chevrolet Blazer, according to two sources close to the project.
The base engine will be GM's new global double-overhead-camshaft four-cylinder known internally as the L850. A V-6 also will be offered, but with a more conventional step-ratio automatic transmission to handle the greater torque.
The vehicle will feature an all-wheel-drive system supplied by a joint venture between Visteon Automotive Systems of Dearborn, Mich., and New Venture Gear Inc. of Troy, Mich.
Despite their growing popularity in Europe and Asia, CVTs have had a tough time penetrating North America. Last year, 270,000 passenger cars in Europe and Asia were built with CVTs, according to the Autofacts Group of PricewaterhouseCoopers LLP in Detroit, but just 10,000 vehicles built in North America had the feature.
Currently, only the Honda Civic HX coupe is offered in the United States with a CVT. Ford Motor Co. is preparing to equip vehicles with a CVT supplied by a joint venture with ZF Friedrichshafen AG starting in late 2001.
GM has said its belt-and-pulley CVT design promises a 7 percent fuel economy gain over a conventional four-speed automatic transaxle - about equal to the fuel economy gain from a five-speed manual transmission.
LITTLE COST SAVINGS
Compared to a conventional transmission, a CVT is simple. The major components are two pulleys and a steel belt. The belt rides higher or lower on each pulley as the pulley is compressed or expanded under oil pressure controlled by computer, constantly changing the speed ratio between the input and output pulleys.
But the Saturn CVT will offer little if any cost savings, said a source at GM.
That's because the company plans to equip its CVT with a conventional torque converter to both de-clutch the transmission at idle and improve launch feel. A CVT can be de-clutched other ways, but a torque converter can almost double the engine torque applied to the transmission under hard acceleration - but at higher cost.
Also, the steel belt that drives the CVT is expensive. It will be supplied exclusively by Van Doorne Transmissie BV of the Netherlands and account for up to 30 percent of the transmission's price tag.
Cost is one reason GM's Powertrain group is having a difficult time selling the design to product planners at GM's other divisions, said a source at Saturn.
Because it has fewer parts than a conventional transmission, the source said, 'the CVT should be incredibly cheaper, but it turns out it's not.'