Twenty miles southeast of Tokyo, about 1,750 cars a day roll out of the Zama factory owned by Nissan, Japan's second largest automaker.

At Zama an amazing 96 percent of all the welds in the body assembly shop are produced by robots. The Zama output comes to a spectacular 67 cars per live worker per year -- almost 50 percent greater than the Japanese auto industry average of 45 cars per year.

In the United States, which lags far behind Japan in "robotizing," average productivity per worker per year is only 25 cars. In Europe, the productivity is even lower; in West Germany, for example, it stands at 11 cars per year.

World industry is on the verge of a boom in developments of robots and robot technology. Although precise figures are not available, U.S. government and private estimates indicate that 16,000 robots now are at work around the world -- 13,000 in Japan, 2,000 in the United States and fewer than 1,000 in Europe. 1

The robots that already exist -- about half of which work on auto assembly lines -- have acquired a 'sense of touch' and a 'sense of sight' through TV cameras.

Robots also have acquired micro-processor "brains" that allow them to switch their programs automatically. For example, a single robotized line at Zama turns out about 50 varieties of Nissan cars, marketed in the U.S. under the Datsun name.

With that background, it is not surprising that as the United States enters what may be a deep recession with domestic auto output down to half of normal levels, Japanese auto exports are moving along unchecked.

So far this year, imports have captured about 26.5 percent of the U.S. market -- and more than 8 out of every 10 imported cars are Japanese. Thus, Japan alone has cornered close to 22 percent of this year's U.S. car market, compared to 17 percent last year.

The grim situation for General Motors, Ford, Chrysler and American Motors is really worse than implied by these figures, because "domestic" output now includes Volkswagen's growing U.S. subsidiary.

At VW's New Scranton, Pa., plant, the company last year boosted its output to 175,170 automobiles -- the equivalent of more than half of its U.S. sales for the year. Last week, encouraged by its U.S. successes, VW announced that it would invest close to $800 million to open a second plant at Sterling Heights, Mich.

VW sales in the United States are still relatively small as compared to Japanese sales -- led by Toyota, Nissan, Honda and Mazda -- of 2.1 million cars here last year.

U.S. and Japanese officials have discussed the Japanese import "problem on a nonstop basis since the beginning of the year, when the latest round of oil price increases announced by the Organization of Petroleum Exporting Countries pointed up the U.S. auto industry's unreadiness to cope with the demand for small cars. No real solution has appeared and none is likely to do so.

Given the inability of U.S. manufacturers to meet the demand for the kind of small, fuel-efficient cars produced by the Japanese, it is little wonder that the United Auto Workers Union has passionately begged the major Japanese car makers to open up U.S. assembly plants, and sought -- unsuccessfully so far -- the support of the Carter administration in curbing Japanese sales here.

Rep. James Jones (D-Okla.), chairman of an influential House Ways and Means trade subcommittee, supports the Japanese companies' resistance to UAW demands that they build plants here. Jones agrees with the Japanese argument that by the time such plants come on line in two to three years, they would run into problems of excess capacity. Jones -- and the Japanese -- assume that U.S. industry by that time would finally have retooled from bigger cars to smaller ones.

But Jones, with support from President Carter's trade representative, Reubin Askew, is pushing a compromise proposal under which Japan would undertake to produce in the U.S. most of the spare and repair parts needed to keep the growing fleet of 12 million Japanese cars and trucks on U.S. roads.

Jones told The Washington Post that within the next four to five years, the demand for Japanese car parts -- now produced exclusively in Japan -- will rise from an annual sales volume of $1.6 billion to about $8 billion. The latter figure is roughly equal to the existing trade deficit with Japan on new cars and trucks. (Overall, Askew estimates the U.S. trade deficit with Japan at $9 billion for 1980, up from $8.7 billion in 1979.)

For the United States, Jones said, one big advantage to producing Japanese parts -- as opposed to cars -- in the United States is that parts production would be labor-intensive; that is, create a lot of jobs.

"The UAW is dreaming," Jones warned, "if they think that one of the new Japanese (auto manufacturing) lines like Zama would create a lot of jobs here." The Japanese are considering the parts proposal as a politically acceptable solution to a difficult problem, Jones said.

Neither Congress nor the White House has bought the UAW argument -- yet. While going through the motions of pressing Toyota and Nissan to follow Honda's lead in deciding to build cars here, Askew and Hormats strongly resist any suggestion of quota limits, voluntary or involuntary.

But Askew and Hormats do recognize that protectionist sentiment could rise this summer. The nation seems headed for a much deeper recession than was forecast even a few weeks ago, and unemployment lines in the mid-West in the midst of a presidential election campaign would intensify cries for a reduction in Japanese imports.

But a successful protectionist effort, Hormats said, would shut off a source of fuel-efficient cars at a time when "domestic manufacturers cannot meet the demand for most types of smaller cars, while having excess capacity to build large cars."

It is Detroit's excess capacity -- not Japanese imports -- that is responsible for the growing layoff rate. U.S. auto manufacturers, Hormats said, "were unprepared for the 1979 oil crisis, with its accompanying swing in demand to energy-efficient cars." For example, Chrysler contracted with VW for only 300,000 engines for its popular small Omni and Horizon cars. It could sell double that number if it had them.

Things are in a process of change, but the hard reality over the next couple of years is that Japanese cars, other small imports and domestically-produced VWs will be needed to supply the demand that Detroit can't fill.

Hormats estimates that it will take until 1982 for U.S. small car output to increase from 1979's 40 percent of the total, to about 50 percent. That would provide an extra 1.6 million domestic small cars.

There will be a shift toward front-wheel drive and other technological advances, long since pioneered by foreigh car makers, that yield significant gasoline consumption savings.

Massive economic problems will remain. Both the automobile industry and the unions see the United States declining in importance as a percentage of the world market. This will lead, says UAW Vice President Irving Bluestone, to the development of world cars, "automobiles that can use parts built in any place in the world, sent to a common assembly point, but together, and sold."

GM's Chevette, the popular Ford Fiesta are the prototypes of world cars -- whose growth is bound to affect production and jobs in the United States.

Yet another factor will affect the U.S. automotive job market -- the robot. Far behind Japan now, U.S. companies (notably GM) are blueprinting plans that will make their production lines 90 percent computer-controlled before the end of this decade.

To the UAW, robots and automation loom as a major threat to jobs. The union already is gearing up to meet "the technology challenge" by bargaining for reduced hours and retraining. There will be more talk of a four-day week (or shorter), and an effort to duplicate the "technology schools" initiated by unions in Sweden and other European countries.