The Supreme Court ruling yesterday overturning the government's attempts to scrap passive restraint regulations could hasten the day when air bags or automatically closing seatbelts are found in most American cars.

It could also bring a major windfall to Ford Motor Co., the automaker that stands to gain the most from such a development.

Both automakers and passive restraint advocates agreed yesterday that the court's decision does not speak on the merits of air bags and automatic belts.

Nor does the decision set a timetable for making that safety technology available to the American public, the two sides said.

But in striking down the National Highway Traffic Safety Administration's reasons for withdrawing the regulations, and ordering the agency to review the matter, the court has set the stage for a major push to get passive restraint rules on the books quickly, advocates say.

"If the agency acts consistently with the court's opinion, it'll move swiftly to set up a passive restraint program," said Michael Sohn of Arnold and Porter, whose firm represented State Farm Insurance Co. as an advocate in the case.

"If the agency does not move quickly, the appellate court will be asked to review the matter," Sohn said, referring to the U.S. District Court of Appeals here, which originally cited NHTSA for failing to provide adequate reasons to get rid of its regulations.

The rules requiring new cars to be equipped with air bags or automatic seat belts, beginning with 1982 models, were withdrawn by the NHTSA in October 1981--largely because of opposition from domestic automakers.

Ford had also been in the anti-regulation camp. But the company continued working on airbag safety devices while its domestic competitors either scaled down or abandoned their efforts.

Now, Ford stands as the only bidder on what could become at least a $50 million contract to provide the government with $5,000, 1985 model, air-bag-equipped sedans.

The purchase would be made by the General Services Administration in conjunction with the NHTSA. The federal agencies, at the urging of Ralph Nader and other consumer advocates, adopted the procurement plan when it appeared that there was no other way to get passive restraints into cars.

The idea was to provide a market incentive for automakers to produce air-bag-equipped cars. The hope was that a huge federal purchase of such cars would lead to similar fleet sales.

But Ford was the only taker. General Motors Corp., Chrysler Corp., and American Motors Corp. all bowed out of the running, saying that the government's order was too small to justify production costs.

Ford also was concerned about production costs, but chose, instead, to work closely with the government in what would amount to a major field test of the benefits or failings of airbag equipped cars.

"The court's ruling makes this kind of test even more necessary," Jerald F. terHorst, Ford's Washington spokesman said yesterday. "It is essential that we achieve some kind of real-world experience on the road with air bags. It is essential to the NHTSA's rulemaking process and it's essential to the industry," terHorst said.

If, as the advocates believe, political pressure or the appelate court forces the NHTSA to quickly implement passive restraint rules, Ford conceivably could reap a public relations benefit as the company that did not have to be pushed.

GM, Chrysler and AMC, meanwhile, yesterday reiterated their longstanding opposition to passive restraints.

Chrysler, the third largest automaker behind GM and Ford, said in a corporate statement that the court's decision "was surprising and disappointing."