A fledgling business lobbying group, whose leaders include former Treasury Secretary William Simon, took out a full page advertisement in The Washington Post yesterday to argue against government aid to Chrysler Corp.

"Bailing out Chrysler with taxpayers' money would be a big mistake," the Council for a Competitive Economy said. "Such a bail-out would be another giant step away from a free, competitive economy."

The council, which has an office on Capitol Hill, was organized about a year ago "to provide a different business voice than the one usually heard, said staff member Thomas Palmer.

"Most business groups, the NAM (National Association of Manufacturers) and the Chamber (of Commerce) speak very eloquently about free enterprise, but everytime you see them in Congress they have their hand out," said Palmer.

The group's ad carried no names, but Palmer said its directors include Simon, Herbert Cornuelle, chairman of Dillingham Corp., a $1 billion-a-year construction company based in Hawaii; D. W. Gifford, head of Gifford Hall & Co., a Dallas builder; Charles Koch, chairman of Koch Industries, a Wichita oil exploration and construction company; Sam Husband, Jr., a vice president of Dean Witter executives of medium-sized businesses.

Although the anti-Chrysler ad was the group's most visible effort so far in Washington, Palmer said the council has bought radio spots and prepared two reports criticizing President Carter's synthetic fuels program for involving government in business matters. The group will issue a report on Chrysler next week.