Takashi Ishihara, president of the Nissan Motor Co. Ltd., is a blunt-talking, aggressive auto tycoon who would fit in well in Detroit -- in Detroit, that is, when it was making money and looking ahead to the next successful model year.

Nissan, now No. 3 in the world, behind only General Motors and Toyota, last year turned a profit of $409 million on sales of $14.4 billion. In January, Nissan broke ground in Smyrna, Tenn., for a $500 million truck plant that eventually will supply all the trucks the company sells in the United States.

Ishihara is angry at his own government for having acceded to American pressure earlier this year for a "voluntary" quota limit on the sale of Japanese cars to the U.S. market. He doesn't think this or any other protectionist measure will revitalize the U.S. auto industry. What's needed, he says, is for the companies and the unions in the United States to sit down "and forge a new relationship."

I asked Ishihara what advice he would now give to his suffering fellow auto executives in the United States. "They should make better quality cars," he said without hesitation. (The small number of American cars that are imported here are virtually disassembled, put back together and repainted before being put on Japanese roads.)

Like other Japanese industrialists, Ishihara is firmly convinced that the Japanese penetration of the American and European markets is the simple end result of greater productivity and sustained high quality.

Nissan Co., for example, brags in its plant brochures that 10 percent of its work force "does not produce anything," meaning that these workers devote full-time to checking and rechecking every car as it comes off the line. I saw this process at the robotized Zama plant and again at the Oppama plant, where sophisticated testing equipment is used.

When Ishihara calls for "a new relationship" between American management and labor, he of course is talking about productivity. The ministry of labor here recently published a meaningful statistic that says a lot: In 1977, the average Japanese worker produced 33 cars a year, compared to 26 for the American and only 16.5 for the German worker. Given the Japanese advances in robot-assembly techniques and other technology, the edge probably has increased even further.

For the manufacturing industry as a whole, productivity per worker has increased at the stunning annual rate of 9.3 percent during 1975-80, against only 1.6 percent in the United States (which is an even sorrier performance than Britain's 2.1 percent average gain).

Thus, measured against wage increases averaging 8.4 percent in Japan and 8.5 percent in the United States, the result is that unit labor costs for manufacturing in Japan actually have declined an average of 0.8 percent in this five-year period while they have risen 5.8 percent in the United States.

The Nissan boss doesn't think American auto management and labor, although they obviously are trying, are yet ready to meet Japanese quality and productivity standards. His somewhat sour view of American workmanship is one reason Nissan has shied away from building cars in the United States, although the company is willing to try its hand at trucks.

Ishihara is blunt about it: Trucks, he says, have fewer components and are easier to maintain than cars. And because they have a longer life cycle, it is easier to improve the production process. In other words, Ishihara thinks "there is less risk" that auto workers in the United States will botch up the quality level of Nissan trucks.

He dismisses a reporter's suggestion that Sony has managed to get high-quality production in its San Diego electronics plant. Ishihara argues that TV-set manufacture is simpler than making a car -- and notes that, in any event, there is a high percentage of Asian workers in the San Diego Sony plant.

Where did Detroit go wrong? Ishihara thinks the American companies' downfall began with their thirst for huge profits on the big-bodied gas-guzzlers before the oil "shock" transformed the market. They ignored small cars to concentrate on the big ones with the large profit margins.

"In other words," Ishihara said, "the Detroit manufacturers enjoyed a monopoly in big cars, and could sell them at a high, monopoly price. So their competition was only among themselves, not with European or Japanese producers.

"Because of the huge profit coming from the sales of the big cars, they were able to give the United Auto Workers a wage that is much higher than the average manufacturing wage in the United States -- I understand 70 to 80 percent higher."

Some auto industry analysts in the United States think it may be 1985 or 1986 before American companies catch up with the current state of the Japanese automotive art, already heavily reliant on sophisticated on-board microprocessors. Some think only General Motors may be able to survive profitably.

The most pessimistic scenario has the Ford Motor Co. dropping entirely out of the U.S. domestic passenger-car business, attempting to stay in the black by concentrating on U.S. truck production and on its profitable overseas car business.