Within just a few months, General Motors Corp. could begin breaking ground on up to three all-new assembly plants to build a series of small vehicles in the U.S., an executive who heads up the automaker's controversial “Yellowstone” program says in an interview.

The Yellowstone project, which encompasses both of GM's new Delta and Epsilon car platforms, is controversial because it is designed to have outside suppliers provide 15 built-up modules — including the interior cockpit, doors, headliner, seats and front and rear suspensions — to the final assembly plant.

Yellowstone potentially is GM's most wide-ranging manufacturing program since the automaker launched its $7 billion GM10 midsize car at four U.S. plants in the mid-1980s.

The project go-ahead and groundbreaking decision await labor deals with the United Auto Workers locals that represent employees at the Lordstown, OH, and Lansing, MI, plants, which GM wants in hand by the end of March, says Mark T. Hogan, vice president and head of GM's Small Car Group.

Mr. Hogan says at least parts of the Yellowstone design and production philosophy will be involved at two or three new assembly plants: the Saturn Corp. facility in Spring Hill, TN; the GM-Suzuki Motor Corp. CAMI Automotive Inc. plant in Cambridge, Ont.; GM's Ramos Arizpe, Mexico, facility and at least two Adam Opel AG plants in Europe.

GM already has sites picked out for the new plants, which would be located in a 50-mile (80 km) radius of Lordstown and Lansing, Mr. Hogan says. Each of the new facilities would be capable of building 215,000 to 220,000 vehicles annually on straight time and about 250,000 per year with overtime. The plants, which also would house stamping operations for major panels, would be one-third the size and require one-third the workforce and investment of GM's most modern U.S. plants today.

Although Mr. Hogan won't say specifically how many models Yellowstone will spawn, the program involves two car platforms, Delta and Epsilon. Delta will be used as the basis for replacements for the Chevrolet Cavalier, Pontiac Sunfire, current Saturns and Opel Astra. Epsilon will form the underpinnings for the Opel Vectra and Saturn LS. The programs involve several body styles and derivatives, including crossover-type car/truck hybrids, the GM executive says.

If Yellowstone works, GM likely will apply the design and production formula to more up-market vehicles, Mr. Hogan says. “But we've got to be pragmatic with what the supply base can do and how we can apply (the concept) to brownfield plants. I'd characterize this as being pretty aggressive just to do three (new) plants this way.”