The long-controversial air bag may be doomed as a future automotive safety option, yet:
* Mercedes-Benz of North America will offer a driver-only, air-cushion protective system in some '84-model cars in the United States starting next fall.
* Ford Motor Company is expected to supply some 5,000 air bag-equipped compact cars for US government evaluation in 1985.
The entire passive-restraint issue, which includes air bags, is before the US Supreme Court. Oral hearings will be held April 26 at 10 a.m. Then the court will decide whether or not the Reagan administration acted properly in 1981 when it rescinded the passive-restraint standard as part of its drive to deregulate the auto industry. The issue has been bouncing around for the past 15 years.
Perhaps no safety device has been more controversial than the so-called air bag, which deploys in a split second in a head-on or angular crash, thus cushioning the front-seat passengers in an automobile. The system has been promoted heavily by the insurance industry, notably Allstate, the Sears, Roebuck affiliate.
The National Highway Traffic Safety Administration (NHTSA) scuttled the passive-restraint rule in the fall of 1981. State Farm Insurance Company and the consumerist Center for Auto Safety appealed to the US Court of Appeals for the District of Columbia, which reinstated the rule, saying the safety agency had acted in an arbitrary manner.
The rule calls for the installation of passive-restraint safety systems in cars, either air bags or automatic safety belts, starting next fall. The federal government and US automakers asked the Supreme Court to rule on the case and the court agreed. Then the appeals court withdrew its order which reinstated the rule.
The case still has a long way to go, according to Helen O. Petraukas, vice-president of environmental and safety engineering at Ford.
''Whether the Supreme Court upholds the Court of Appeals or rules against it, the thing has got to go back to NHTSA for more rulemaking so that we know the kind of a rule we have to comply with if there is one,'' she asserts.
Meanwhile, Daimler-Benz, the West German auto manufacturer, has already sold a few thousand air-cushion systems in Western Europe, the only carmaker to offer the passive-safety system in its production cars.
The Mercedes-Benz system consists of a standard three-point manual safety belt supplemented by an air bag and knee bolster on the driver's side. On the front-passenger side, however, only a three-point belt will be provided, according to Walter Bodack, president of Mercedes-Benz of North America.
In the 1984-model year, he says, ''about 5,000 air-bag cars will be offered, with additional units to be provided depending on the market response.'' Plans now call for the passive air bag system to be extended in 1985 to the 380-SL and , a year later, across the entire line. It all depends on how well the option sells.
Honda last fall showed an Accord with hand-tooled air bags and experimental knee bolsters at an international conference on auto safety research in Kyoto, Japan. The company, however, is a long way from offering air bag-equipped cars to the public, a Honda official said at the time.
General Motors sold about 12,000 air bag-equipped cars over a three-year period in the mid-1970s, but the carmaker dropped the option because, it said, the demand was insufficient to warrant its continuation. At the time some critics charged that the option was not promoted.
The NHTSA will pick up the tab for the forthcoming government-sponsored air bag test. Budget funding for the test in fiscal 1984-85 is $2.5 million - or $ 500 per bag. Like the Mercedes-Benz air bag, it, too, will be installed only on the driver's side of the vehicle.
''We're doing all of the work we can so we'll be ready to bid,'' says Ms. Petraukas of Ford. ''We're hoping it might be as early as May.''
The air bag installation is expected to be on a compact-size car, ''because that's what the GSA (General Services Administration) specifications require,'' she adds.
She says the biggest issue with the air bag is the system's effectiveness. The auto industry generally maintains that a properly worn safety-belt system is more effective in a mishap than an air bag. The air bag, for example, is effective only in frontal and front-angular impacts, but not in rear-end impacts , side impacts, and rollovers.
''The beauty of the GSA fleet,'' Ms. Petraukas says, ''is that it opens up the opportunity to try to do other fleets as well. Obviously, the more cars you add, the more experience you have in a shorter time.''
The Ford environmental-safety executive says she is convinced that ''we're coming up on an era where there's a consumer awareness of safety.''
While she concedes that the air bag ''certainly is equated in the consumer's mind with safety, there are so many other things, constructional things, that one could do to a vehicle that will improve its safety.''
Too, there's something the motorist himself can do, she adds. ''Fatalities could be cut in half if everybody wore the safety belts,'' she stresses, adding: ''In Ontario (which has a mandatory safety-belt law), belt usage is impressive.''
The Ford executive says the company ''has been active in a number of state legislatures in trying to get mandatory seat-belt legislation. I'm convinced that the key to it is to do what the Canadians did, and that is really do an extensive public relations program so that there's more receptivity.''
As for improving the design of cars, Ms. Petraukas says that ''we could do more in the design of the steering column. The domestic auto industry already has a coordinated research program under way with NHTSA.''
Some of the breakthroughs in electronics now make antiskid brakes more promising, she continues. Mercedes-Benz already offers such a system in Europe.
''Everyone likes to believe that there's an instant solution to the problems with the automobile,'' Ms. Petraukas asserts. ''I don't think there is. I'm convinced that the things we're going to see in the future are going to be more in the way of refinement, or evolution, rather than major breakthroughs.''
Optimistically, she concludes: ''I think we're coming up on an era where safety can be a competitive feature of a vehicle.''