General Motors Corp. will build a 1985-model mini-van at its Broening Highway plant in Baltimore, reliable auto industry sources confirmed yesterday.

The decision will put Baltimore in the middle of a multibillion-dollar battle for the domestic auto industry's newest, and potentially one of its most lucrative, market segments.

The mini-van is designed to have the passenger capacity of a station wagon, some of the cargo space of a regular van, and the large size of neither. Unlike regular vans, the mini-van fits into an ordinary garage and drives like a mid-size car.

GM, the nation's largest automaker, will be playing catch up. Chrysler Corp., the third largest automaker, will introduce the country's first mini-van this fall.

"There's no doubt about" GM's intentions to begin mini-van production in Baltimore, one well-placed industry source said yesterday. "They'll start producing mini-vans in Baltimore next year for introduction in the the fall of 1984 as 1985 models. The van will be built at Broening Highway," the source said.

Confirmation also came from sources at Hoover Universal Inc., of Ann Arbor, Mich., which plans to build a $5.5 million factory in Belcamp near Baltimore to produce seats for the mini-van. Hoover officials said yesterday that their new plant will create 85 jobs, and that it will be one of several new GM supplier plants to be built in the area. Another manufacturer, Monarch Molders, of Dayton, Ohio, also plans to build a plant in Baltimore to supply the GM operation, according to already published reports. Monarch officials could not be reached for comment yesterday.

GM plans to incorporate some aspects of the "just-in-time" inventory system in its Broening Highway operation. That means the company wants as many of its suppliers as possible within an eight-hour delivery distance, which would help GM keep down inventory costs, sources said.

GM is investing $270 million in renovating the Broening Highway plant, which currently produces intermediate, rear-wheel-drive Chevrolet Malibus and Monte Carlos. It was unclear yesterday whether GM would continue production of those cars in its Baltimore plant.

However, sources point out that GM's planned mini-van will use rear-wheel drive--which means the company could produce all three lines in the same plant, the sources said. GM spokesmen declined comment, citing what they said is the company's longstanding policy against public discussion of specific future product plans.

Chrysler's mini-vans--the Dodge Caravan and Plymouth Voyager--will be front-wheel-drive vehicles using 2.2-liter, 4-cylinder engines. Chrysler also plans to use a 2.6-liter, 4-cylinder engine from Japan's Mitsubishi Motors Corp. Ltd. in some of its mini-vans. The Chrysler vans are designed to get 25 miles-per-gallon on the highway, which approximates the fuel economy of many standard-size passenger cars.

Of the $700 million Chrysler invested in its mini-van program, $400 million went into renovating its plant in Windsor, Ontario, where the Chrysler mini-vans are being built.