THE PROBABILITY of import restrictions on foreign cars seems to be fading rapidly. That's fortunate. Far from providing an interval enabling American companies to catch up, it would reduce the pressure on them to change. It would invite procrastination in the expensive and difficult transition through which they are now passing.

The latest setback to the protectionist cause is a preliminary study written by the staff of the federal International Trade Commission. The ITC has the job of weighing the industry's claims that it is being injured by foreign competition -- claims pressed, in the this instance, by the United Automobile Workers and the Ford Motor Company. It's quite true that sales of imports have gone up while sales of American cars have gone down. But not so fast. The ITC's staff points out that the sales of all small cars have rising -- domestic as well as imported. The drop is wholly in the sales of the large cars. Meanwhile, the entire market for cars has been depressed by the recession, which has very little to do with the question of imports.

It's also true, as the UAW argues, that employment in the American auto plants is down. The ITC staff study observes that average compensation for labor in those plants went merrily up 9.4 percent a year through the late 1970s, while productivity -- the number of hours of labor to produce a car -- remained flat. Here the figures show the same pattern as in steel, another industry bellowing for protection from imports. When companies keep giving wage increases with no relation to productivity, and no regard to loss of competitive strength, is there a public responsibility to protect them from the consequence at the consumers' expense?

If they can keep their costs under control and raise productivity, the American automobile manufacturers' troubles are likely to prove temporary. Both Ford and Chrysler are now putting their next generations of small, high-mileage cars into their showrooms. Another family of small General Motors cars will arrive next spring. Constraints on supplies of small domestic cars are already easing, and the American industry is now about to get help from an unexpected source.

For years the manufactures have complained bitterly about the safety regulations imposed upon them by the Department of Transportation and its National Highway Transportation Safety Agency. The NHTSA has been publishing, in installments, the results of its extensive crash tests. It is rapidly working toward a complete system of safety ratings for every car model, domestic and foreign, by size and weight, similar to the gasoline mileage ratings that the government already publishes. While the imports have usually excelled in fuel efficiency, the domestic cars in general seem to be winning significantly higher scores in safety. These safety ratings will force the manufacturers -- and not only the Americans -- to complete in raising their customers' chances of surviving serious collisions. That's competition at its fairest and healthiest.