Trade Representative Bill Brock launched a new drive against congressional efforts to restrict car imports from Japan and elsewhere. He was responding to a new attempt in Congress to win approval of the so-called ''domestic-content bill.'' That would require cars sold in this country to be made substantially with American parts and labor. ''This bill would raise the price of every car, cost jobs, and start a trade war,'' Mr. Brock told a House commerce subcommittee. ''It is the worst piece of economic legislation in a decade.''
The administration stalled similar legislation last year after it passed the House and the bill died. Mr. Brock favors voluntary restraints, such as the recently announced decision by Japan to extend through next March its voluntary limit on car exports to the US. Japan is holding such exports at 1982 levels, but it already has about 20 percent of the US market.
Many in Congress have complained that the flood of cars from Japan is the source of the problem. But Brock blames high oil prices, government regulation, changes in consumer demands, and the low value of the Japanese yen against a strong dollar, which makes Japanese cars cheaper in relation to American-built vehicles.