AUTOMOBILES BUILT in this country over

the past several years have proved significantly safer than those from Japan. That conclusion had emerged earlier from the federal government's experimental crash tests. Now it is confirmed in an analysis of actual accident data by two related research organizations, the Insurance Institute for Highway Safety and the Highway Loss Data Institute.

These studies compare the records of fatalities and of injury claims. In comparison with the Japanese cars, the safety performance of the American cars was, in general, strikingly better. The American manufacturers have greeted this finding with the embarrassed silence with which, by long tradition, they respond to all mention of accidents and safety.

If these studies had shown that their cars' fuel efficiency was exceptionally good, or that their resale values were unusually high, the American companies would have embraced them in vigorous advertising campaigns. Their reaction to the safety reports is a commentary on the curious psychology of the American automobile companies themselves. It is characteristic of them that their cars are unusually good in this respect, and yet they are unable to bring themselves to say so out loud--much less try to sell cars on their ability to protect their occupants.

Since the manufacturers remain gagged by habit, the insurance industry--to its great credit--is now publishing the injury losses by make and model. It is true that small cars tend to be less safe than large ones. But it is also true that design makes a tremendous difference. A carefully built subcompact will have a better safety record than many larger cars. Even among structurally similar cars--for example, General Motors' X-car line--disparities in insurance claims suggest that a minor difference in interior trim or the shape of a dashboard can be crucial in a highway crash.

Since some 51,000 Americans died in highway accidents last year, perhaps it is also worth noting that no manufacturer is yet building cars fully as safe as present technology can make them. Under the current administration, the Department of Transportation seems to have lost interest in the subject, but in the 1970s it actually built a trim little car known as the RSV--the Research Safety Vehicle--capable of providing its passengers with better protection, in a crash than any car now in production. It looks like a sports car, and it gets 40 miles to a gallon of gas. It exists in prototype. Why can't you buy it out of the showroom? Ask the auto industry.