Is General Motors ''jumping the gun'' as it pushes its new-model cars onto the road? The world's biggest carmaker faces the potential recall of hundreds of thousands of X-body compact cars, such as the Chevrolet Citation and Oldsmobile Omega, for an alleged brake problem, if the National Highway Traffic Safety Administration (NHTSA) rules in favor of the Center for Auto Safety (CAS), a consumer group based in Washington, D.C.
Balky diesel engines, faulty transmissions, underpowered J-cars, and now the brakes on its front-drive compact X-cars - all have come in for repeated salvos from angry motorists, vocal consumer groups, and militant activists. As for the subcompact J-cars, people just didn't buy them.
In all cases General Motors denies any major fault.
At issue in the NHTSA brake study is the alleged tendency of the rear wheels of the X-cars to lock up under severe brake pressure and throw the vehicle out of control. Originally the problem was believed limited only to 1980-model X-cars with manual transmissions.
Last month the NHTSA responded to a petition from the CAS to extend its investigation to include not only the 1980-model cars, but also 1981-83 cars.
Now the NHTSA, in the final stages of its investigation into the problem, has urged GM to review its position on the brake issue.
''We've asked that its response include a discussion of what added corrective actions it might take to solve the problem,'' says an NHTSA spokesman.
GM, for example, has been asked for data on the number of 1980-83 X-body vehicles it built, broken down by make, model, model year, plant of manufacture, type of transmission, etc., as well as information on how many complaints it has had, plus reports of any accidents, fatalities, and injuries.
NHTSA expects a reply by GM ''within a couple or three weeks.''
If GM does not respond, the NHTSA investigators will make a recommendation to the head of NHTSA, who then has to rule on the validity of the complaint. He then could order a recall. If the issue goes to court, NHTSA will have to prove that there is, in fact, a safety-related defect.
GM already had voluntarily recalled 47,000 cars built in 1980 and says it believes it has fixed the lockup problem. But the NHTSA says the problem has not been repaired. GM built 1 million X-cars in 1980, only 200,000 of them with manual transmissions.
General Motors, says Clarence M. Ditlow III, an engineer and head of CAS, didn't take the time to go to a load-sensitive proportioning valve when it introduced the X-body car. ''That was a dumb thing to do,'' he charges. The purpose of the valve is to funnel more brake pressure to the front-wheel brakes, where the car is heavier, and less to the lighter rear end.
The X-car, which had less than a smooth launch when it was put on the road in April 1979, was the first small front-drive car for GM, which ''just didn't have enough time to fine-tune the braking system,'' Mr. Ditlow adds.
The brake-lockup problem, in fact, is just one more bad-news story for GM.
The diesel dilemma stems from the 5.7-liter gasoline-engine-converted diesel that GM rushed to market in 1978 in order to upgrade the mileage figures for its large cars. US fuel-mileage requirements were getting tougher each year.
Peter and Diane Halferty of Seattle complain that their early-model, $20,000 Cadillac Seville ''self-destructed'' after 3,000 miles. In response, the couple organized Consumers Against General Motors and sued.
''Both the diesel problem and the X-car brakes can be traced to GM's speed in trying to bring the cars to market,'' Ditlow says.
As for the transmission issue, lawsuits have been filed in a number of states , including New York and New Jersey. ''It's hard to prove,'' asserts Samuel H. Smith, supervisor of auto affairs for the New Jersey division of consumer affairs, who says the division has received thousands of transmission complaints. ''Right now we're trying to organize the complaints and see how many apply to the GM 200 transmission,'' he adds.
Yet despite the problems which hound GM, the NHTSA now is receiving far fewer complaints from motorists than in the 1970s. Last year, for example, fewer than 2 million cars were recalled for repairs, 1,401,000 domestics and 513,000 imports. ''In 1974, we had 13 million,'' says the NHTSA spokesman.