Boston motorists have long been notorious for turning traffic circles into bumper car rides, New Yorkers for making pedestrians an endangered species. But when it comes to speeding on the open road, California is unsurpassed.

Federal transportation officials recently ranked California the nation's most flagrant violator of the six-year-old 55-mph speed limit -- a rating that could cost the state millions of dollars in federal highway funds.

During the first three quarters of the last fiscal year, only 33 percent of the state's 15.3 million drivers stayed within the legal limit, surveys conducted by the state department of transportation showed.

A major reason, federal officials say, is the fact that for many years -- no one can remember precisely how long -- California has been the only state whose highway patrol is barred from using radar to enforce speed limits on its 4,704 miles of freeways.

During more than two decades, the California Highway Patro, which wants to equip patrol cars with moving radar, has been waging a losing battle with the California Legislature, even though radar has long been authorized for local use in more than 400 cities throughout the state.

The highway patrol contends that radar is a much-needed tool, particularly in a state where freedom of the road is considered sacred enough to make unmarked patrol cars and speed traps illegal.

But there is strenuous opposition, much of which has come from the Teamsters union. In recent years, however, the major stumbling block has been a San Francisco Bay area assemblyman who chairs the powerful Rules Committee. Last year, for example, after a resolution authorizing radar passed the Senate and the Assembly Transportation Committee, Assemblyman Lou Papan re-routed the measure to his Rules Committee and sent it to the dust heap.

The legislator, who has been convicted of six speeding violations in the last three years, says radar is "not suited to the highways we have in California," adding that "it has been shown to be 30 percent inaccurate." He cited a case last year in Dade County, Fla., in which a judge threw out a radar-clocked speeding ticket.

He insists that his driving record has nothing to do with his attitude on freeway radar. "So I'm not the best driver in the world," he says. "What's that got to do with anything? I'm getting my tickets without radar."

Because of its motorists' defiance of the speed limit, California stands to lose as much as $11 million in federal highway funds. The law allows the federal government to impose up to a 5 percent penalty on states where compliance with the speed limit in fiscal year 1980 fell below 40 percent.

But Robert Beasley, director of special projects for the U.s. U.S. Department of Transportation, acknowledges that the law pertaining to sanctions is probably loose enough to let California off the hook for a year.

Still, Beasley warns that next fiscal year, by which time the states are supposed to have increased compliance to 50 percent, California may really be in trouble.

"Radar is certainly a deterrent.Without it, you're handicapped," says Beasley.

He cites the example of Maryland, the state with the best compliance record, where state police are allowed to trap speeders from an array of unmarked vehicles, including hay wagons and tractor-trailers. During the first three quarters of fiscal 1980, 71 percent of Maryland's motorists obeyed the speed limits.

But Papan, for one, hopes that the 55-mph limit, which he likens to Prohibition, will soon be a thing of the past. The Democratic lawmaker is counting on President-elect Ronald Reagan, who has said states should set their own speed limits.