Transportation Secretary Brock Adams told automobile industry leaders yesterday they must do nothing less than "re-invent the car" in the next few years. He suggested a government-industry "summit" next year to begin the technological revolution.

In an unusually blunt speech to the Economic Club of Detroit, with top auto executives in his audience, Adams took note of current unrest in Iran that has curtailed oil production and warned that time is running out for the internal combustion engine.

"We are skating on thin ice. The motor vehicle is the prime mover of our society, and our mobility as well as much of our economy depend on a fragile alliance with the Organization of Petroleum Exporting Countries... events in Iran and the announcement of rationing by American oil companies reinforce my belief that the curtain is quickly dropping [on engines of today] and, the fact is, we have no replacement."

Adams said he would ask auto industry leaders to join with govern7ent planners in a "summit conference" here early next year to determine what can be done together to hasten development of an energy-stretching, life-saving and "people-pleasing" car. Some new initiative is necessary, he said, to end an era of tug-of-war between industry and government. And a cooperative effort that focuses on long-range goals may be a better approach than government mandates and regulations, Adams asserted.

But the situation today, according to Adams, is this: "In recent years the American autamobile industry, I regret to say, has acquired a reputation for imitation, not innovation. The companies have become collaborators rather than competitors... the industry thinks (of federal standards) as absolute targets and seems to feel little or no incentive to try to gain an edge by exceeding those requirements."

Despite warfare between government and the industry over fuel economy, Adams said Detroit now is producing a car that gets about as many miles per gallon of gasoline as did Henry Ford's Model "A" of 50 years ago.

To reduce trade deficits and confront a future shortage of energy, Detroit must make a "quantum jump forward" in technology since cars are here to stay, Adams said. People can be diverted from their cars only to a limited degree in urban areas where transit is convenient, he added. Copies of his speech were made available in Washington.

Separately, there were these related developments yesterday:

Sales of General Motors cars during November continued at a torrid pace but Ford, Chrysler and American Motors all reported sales declines compared with the same period last year.

Industry leader GM said November sales jumped 12 percent to 472,469 cars or 62 percent of the U.S. market, for the best start of a model year in the company's history. Ford Motor sales dipped nearly 7 percent to 198,990; Chrysler Corp. sales fell 8 percent to 79,715; AMC sales declined 17 percent to 12,790 and Volkswagen of America sold 5,661 U.S.-built Rabbits.

GM raised prices by amounts ranging from $25 to $105 on larger engines purchased as options on 1979 models, to help the firm meet fuel economy standards, discourage motorists from buying less fuel-efficient engines and help recover costs. The increase will boost the price of an average GM car by 0.5 percent.

The National Highway Traffic Safety Administration said it is investigating a suspected safety defect in the steering systems of Ford light trucks and vans, produced from 1974 through 1977.