The joint investigation by D.C. police and the Department of Public Works into allegations of misconduct at the city's two car inspection stations is the latest in a series of recent probes that have led to the resignation or firing of six station employes since 1981, a department spokeswoman said yesterday.

Tara Hamilton said the department sought police assistance in the investigation eight months ago. "We felt there was a need to investigate the operations of the inspection stations," she said.

The investigation was brought to light this week in after a series of reports by WDVM-TV (Channel 9) reporter Mark Feldstein alleging that District taxi drivers have paid bribes to have faulty cabs pass inspection.

The series suggested that payoffs have resulted in dangerous cabs with severe mechanical defects operating in the city. It alleged that drivers give payoffs to "middlemen" who are able to get the faulty cabs through the inspection process.

Hamilton refused to elaborate on the investigation but said that the allegations in the WDVM report "obviously will also become a matter the city is looking into."

"The system has worked like this for years" with little disclosure of it because "drivers are either benefiting or because they're afraid to tell," said Norman Saunders, a member of the 12-person D.C. Hackers License and Appeals Board, which hears citizen complaints.

Saunders, who drove a cab for 10 years, said he once saw a car pass inspection despite "brakes you practically had to stand on them to make them stop."

D.C. City Council member Betty Ann Kane (D-At Large), who heads a committeee with authority over the city's taxi industry, termed the allegations of bribery "an example of why there's a need for consolidated regulation of the taxis."

Currently, the public works department, which supervises the inspection process, the Public Service Commission, the police department and several other city agencies regulate various aspects of the taxi industry. A bill reported out of Kane's committee Tuesday would centralize that power in a taxicab commission.

"If an employe is going to do something dishonest they're going to do something dishonest, but when enforcement is spread around among three or four different agencies something is bound to fall between the cracks," Kane said.

The council approved funds this year to triple the number of hack inspectors who make certain cabs are complying with regulations between the twice-yearly inspections, according to Kane.

Hack Inspector Larry Zirk said yesterday that the current force of four inspectors was not adequate to police the situation. "There's cabs on the street that shouldn't be out there," he said.

Lloyd England, president of the Alliance of Taxicab Businessmen, said he had "heard of cases where certain people can take your car through inspection."

"It's been heard that there are some people who are over at the inspection station quite reguarly and if you give them $25 or $30 or $50 they can take your car and bring it through," he said.

However, England said he had never seen those individuals giving payoffs to inspection station employes in return for stickers. "I don't know if actually anything is being done other than a man taking your car through and you paying him assuming he can get something done," England said.

A District cab driver who declined to be identified said yesterday that he had twice paid $50 to a middleman in order to get an inspection sticker for a car that needed body work that he could not afford.

"He brings the car back a half-hour later with the inspection sticker on it," the driver said. "It was easier to pay somebody to get it through" than to repair the car, the driver said.

William J. Wright, chairman of the Taxicab Industry Group and a member of the board of the Capitol Cab Association, contended yesterday that the disclosure of the bribery allegations was "part of a scheme" by Kane to win approval for her taxi regulation bill. He warned that the measure would "put cab drivers out of business."

Wright said he did not believe bribery was widespread in the inspection process. "That doesn't exist any more than it does in any other business," he said. "I would suppose that restaurants . . . that have to go through inspection, they would give them [inspectors] a cup of coffee."

"I can't say that in no situation no one has ever tried to bribe an inspector," he said. "I don't believe it exists to any extent that would impair the safety of the riding public in Washington, D.C. It's to no one's advantage to bribe an inspector to get an unsafe car through. He's buying a lawsuit if he drives an unsafe cab."

Daniel Smith, president of the Eastern Cab Company, said he had no knowledge of inspectors being bribed. But, he said, his company's cars have lost an average of three inspection stickers a week that are stolen, apparently to be used on cars that are overdue for inspection.