January 18, 1981

TOKYO T HERE was a time when Detroit set out to rule the world. American auto makers built up domestic production, started to export and then followed up by moving plants overseas, to make cars and trucks within the markets they served. With this one-two-three punch, Detroit's Big Three became synonymous with American industrial strength, unquestioned leaders in the automotive field. No more, of course. Chrysler is on its knees and both General Motors and Ford have reported huge losses recently. The new world appears to belong to Japan. In 1980, this nation pulled ahead of the American auto industry for the first time, producing 11 million cars and trucks, up 10 percent, while the United States industry turned out just 7.8 million, down 30 percent. Imports captured more then one-fifth of the American market itself, and 78 percent of them were made in Japan. Those represent punches one and two, and on both sides of the Pacific their success is unquestioned, the momentum they have built, unchallenged.

-------------------------------------------------------------------- Annette Insdorf, who teaches film at Yale University, was Abel Gance's translator at the Telluride Film Festival. By ANNETTE INSDORF The provocative combination of Napoleon Bonaparte, a pioneering filmmaker, an indefatigable film scholar and an enthusiastic advocate named Francis Ford Coppola requires an appropriate stage on which the dramatic history of nations as well as films can be played out. These individuals - Corsican, French, British, and American respectively - have found their site: Radio City Music Hall, where the reconstructed version of Abel Gance's groundbreaking 1927 ''Napoleon'' will have its New York premiere Friday, Saturday and Sunday. The film, prized by scholars and other filmmakers for its innovative techniques, traces the career of Napoleon from his school days to his military triumphs. It is also a love story in which the hero of the battlefield is reduced to a fumbling swain.

ART in the the suburbs has found a new base of operations - in the local library. Those hushed sanctums, once reserved for scholarly pursuits, now quake with rock music or vibrate gently to the sound of chamber ensembles. Modern-dance troupes vie with budding baritones, poets, celebrity lecturers and theatrical productions for bookings. Walls are laden with revolving exhibitions of frequently traditional, but occasionally avant-garde, painting and photography. As a result, ''people are in the library who never would have come before,'' said a staff member in New Rochelle. There, former patrons of facilities in Larchmont and Scarsdale are coming to the new downtown New Rochelle facility. In Yonkers, ''We have standing-roomonly for black history and concerts,'' according to a spokesman. In packed auditoriums around the county, film devotees are engrossed in vintage John Ford, contemporary Lina Wertmuller or offbeat originals by local filmmakers. The very fact that art galleries, workshop space, storage for movies, recordings and pictures, auditoriums, lecture and meeting rooms have become an integral part of new library construction and old library modernization is testimony to the changes that have taken place.

FREEHOLD TOWNSHIP ALTHOUGH New Jersey has spent more than 10 years and some $7 million planning a reservoir along the Manasquan River, the project may have to be re-evaluated because the river is so heavily polluted. A report by the Federal Evironmental Protection Agency, a copy of which was obtained by The New York Times last week, disclosed that leachate from an abandoned landfill was ''heavily contaminating the Manasquan River'' with hazardous chemicals, including polychlorinated biphenyls (PCB's) and benzene. Furthermore, an unannounced inspection by the Freehold Township Health Officer here last week showed that ''inadequately treated sewage'' was being discharged into the river from one of several treatment plants known to have been regularly polluting the Manasquan. Some health officials in the area oppose the reservoir because of the quality of the water that would be used. ''The Environmental Protection Agency has done a very thorough study,'' said R. Chadwick Taylor, the township Health Officer, who made the inspection last week. ''But so far, there have been no longterm studies of the river waters to show a trend in the quality one way or the other. We in public health are not too crazy about the idea of a reservoir.''

R ONALD REAGAN takes office this week with no shortage of economic problems and no shortage of advice on what to do about them. Inflation, productivity, energy, growth - they're all crowding for attention. The New York Times turned to the four regular contributors to its Economic Affairs column and asked them two questions: What are the most important things Mr. Reagan should do about the economy? What are the most important things to avoid? The contributors are Lester C. Thurow, 42 years old, economics professor at the Massachusetts Institute of Technology, Rudolph G. Penner, 45, resident scholar at the American Enterprise Institute, and Paul W. MacAvoy, 47, and William Nordhaus, 40, economics professors at Yale. Their replies follow: By LESTER C. THUROW It is your job to tame the four horsemen of the economic apocalypse - inflation, unemployment, falling productivity and easily disrupted energy supplies. But neither you nor any other President is a match for these four horsemen. You must set an order of priority and tame them one or two at a time.