In the United States, American-made parts account for less than half the content of Japanese cars made in America.

Japanese automobile manufacturers bought $19.86 billion of American-made parts and materials in the fiscal year that ended on March 31, an industry trade group said this morning.

Moreover, its purchases of American-made parts have increased fivefold since 1986.

The choice, they say, is between assembling American-made parts in Mexico - thereby retaining some American jobs - or moving the entire manufacturing process farther away.

The Japanese auto makers have also promised to increase purchases of American-made automotive parts to help redress the trade imbalance.

But the legislation that would have required offshore oil drillers to use certain American-made parts never passed Congress.

Critics charge that its employees are overworked and that its cars contain relatively few American-made parts.

In the last fiscal year it bought $2.6 billion in American-made parts.

Mr. Mosbacher adopted this concern today, saying that these companies should rely more heavily on American-made parts.

In opening that market to competition, the United States is relying on expectations that more shops will use American-made parts.