Chrysler Corp. showed off the first of its coming modestly shrunken post-oil embargo automobiles here today, a new Dodge Diplomat and Chrysler LeBaron.

The two new moderately luxurious cars weigh roughly 3,700 pounds and will sell for $5,000 to $7,000 when they reach showrooms in May, said R. K. Brown, executive vice president for North American Automotive Operations.

The new cars are about a foor shorter and 200 pounds lighter than Chrysler's current intermediates like Fury and Monacco, and roughly six inches longer and 300 pounds heavier than the more recent Volare and Aspen.

A four-door station wagon version of the new cars, initially available only as two-door and four-door models, will begin with the first 1978s this fall, he said.

The company is projecting U.S. sales of 80,000 units and up for the first year. The Diplomat and LaBaron are particularly aimed at style-oriented owners of competitive makes, he said.

Asked what is likely to happen if Chrysler cannot meet the new federal fuel economy limits that take effect with the 1978 models, and whether Chrysler might not simply stop production of the bigger cars that burn more fuel, Brown said.

"That's a fascinating subject," he said. "I don't think anybody knows. It si kind on interesting that were the only goddamned industrialized nation in the world that has adopted this kind of law.

"My personal comment: It seems much more prevelent to legislate the manufacturers than the voters," he said.