Smaller Japanese auto companies producing subcompacts for sale in the United States under General Motors and Chrysler nameplates have been given special breaks in the allocation of new export quotas.

The Ministry of International Trade and Industry today officially informed Japan's eight auto exporters of their shares of the 2.3 million-car quota that it has established for the year starting April 1.

Following past practice, the ministry refused to make the numbers public. But they were quickly leaked to Japanese newspapers.

GM's and Chrysler's requests for a total of close to 600,000 "captive imports" -- Japanese-produced cars that they sell as their own -- were cited last month by the Japanese government as a key factor in its decision to raise the quota from 1.85 million cars per year.

Citing predictions of market demand for 2.7 million Japanese cars, Tokyo depicted the decision as a concession to the United States, which is fighting to pare down a $37 billion trade deficit with Japan.

GM has import contracts with Isuzu and Suzuki, and Chrysler has a similar arrangement with Mitsubishi. All three of these Japanese companies are small or medium-size producers.

According to press reports, Isuzu's allocation for captive imports and cars sold under its own name in the United States will rise by nearly two and a half times to about 120,000. Suzuki's will more than triple to 53,000.

Mitsubishi's share of the quota will rise by 50 percent to about 200,000 cars.

Other smaller auto companies will get proportionally large rises, too. Mazda and Subaru both will be allowed to increase their sales by about 30 and 40 percent, respectively.

The industry leaders, Toyota, Nissan and Honda, will have to make do with increases of only about half the 24 percent rise of the total quota.

The smaller companies had charged that the old quota system had frozen obsolete market advantages of Toyota, Nissan and Honda, which between them controlled about 76 percent of the old quota. That figure now will fall.