The 1973-'74 oil shortage saw an upsurge of interest in mass transportation and car pooling. But by 1975, a year after the crisis ended, 85 percent of all Americans were using cars or trucks to go to work and the vast majority drove alone, the Census Bureau reported yesterday.

Department of Transportation experts said it is believed that the use of car pools and mass transit increased in 1973-'74 after the Arab oil embargo and the appearance of long lines at filling stations, similar to those that have vexed Americans in the past few months during the latest crisis.

No one knows precisely how great the increase was, but the Census Bureau survey, first of its kind, shows that it didn't last. By 1975:

Of 80.1 million Americans going to work each day, 52.3 million (65 percent) were driving alone.

Another 15.6 million (19.4 percent) were driving but with other passengers in the car or truck.

Only 4.8 million used public transportation (6 percent) and 3.8 million walked (4.7 percent). The rest used bikes, cycles or worked at home.

The average commuter trip was 9 miles each way and took 20 minutes.

The study shows that, by 1975, the proportion of mass-transit users among those employing vehicles had actually dropped from 10 percent to just over 6 percent.

The census survey also flies in the face of conventional notions about commuting as primarily "commuters pouring out of suburban residential areas each day onto jammed streets and expressways en route to downtown work places."

In fact, the survey showed that more people both live and work in rural areas or live and work in sububan areas than commute between suburbs and inner cities. The reason is that, for a long time, jobs have beenmoving out to the suburban areas and their fringes.

The survey found 20.2 million people who live and work in rural areas and commute. Some 19.3 million live and work in suburbs, sometimes requiring long commutes from one part to another. Another 16.5 million live and work in a city, though this may require substantial trips from one part to another. Only 9.6 million people fit the conventional picture of suburbanites who commute into town to work.

A Department of Transportation expert said it is believed that the gas crunch of recent months saw another very big surge of mass transit use, although nationwide measurements are not available. "The question is whether it will hold this time," he said.

Some surveys by nongovernment groups suggest that use of mass transit may be growing substantially for nonwork purposes like wekend shopping and entertainment.

However, the Census Bureau survey is the most comprehensive for commuting-to-work patterns. Here are the overall figures for 80,125,000 workers in 1975:

Drive alone 52,294,000

Carpool 15,575,000

Public Transport 4,825,000

Bike 471,000

Motorcycle 297,000

Walk 3,778,000

Other 299,000

Work at home 2,585,000