It was Key Bridge and it was rush hour, and that's oil and water any way you mix it. So when Alison Hughes' brand-new gas guzzler decided to catch fire midway across the Potomac, the chaos was neither surprising nor very far behind.

What was a little surprising was the performance of the dealer's service department.

There were huge delays, and diffriculty in finding the trouble, or so he said. Relations degenerated badly after a couple of weeks. By then, it was screams, fists pounding desks and threats to sue.

When the dealer finally summarized matters by saying, "Go ahead and sue me; I've got your damn money," Alison Hughes was "on the verge of a nervous breakdown."

But she went neither to court nor to the funny farm. She went to Northern Virginia Community College. When she emerged a year later, she was a magna cum laude laureate in auto diagnostics.

A year as an auto mechanic followed. Now, this former mild-mannered editor for Congressional Quarterly has one of the newest, rarest and most thankless jobs in the Washington area. She is an ombudswoman for the service department of an auto dealership.

"I had had rotten service and I knew it was rotten service," said Alison Hughes. "So now it's a holy cause with me. I don't mean to put the public in a bad light, but they deserve representation."

What that means in practice is this:

At most auto repair shops, shrieks and death threats from customers are most often heard around the cashier's window. Usually, neither shrieker nor skriekee knows a bloody thing about cars. And no supervisor who does has time to to intercede. So the shrieker goes away mad, and poorer, and maybe his car really isn't fixed right.

At JKJ Chevrolet in Vienna, Va., Alison Hughes and John Connacher either step right up to the cashier's counter when they hear war whoops, or the whoopers are ushered into their nearby office. Their job is first to cool everybody out. Then they do what they can to solve the customer's problem, have the car fixed again, or explain why the customer has just paid a month's salary.

Connacher, 24, who has been an ombudsman for nine weeks, four longer than Hughes, says the job is "really a losing battle.

"The problem is that seven out of 10 people who pull in that lane out there can't afford the car they're driving. Seven out of 10 complaints we get will mention price. Besides, they're all too emotional. They don't realize these are cars, not people."

Still, Connacher and Hughes report that 90 per cent of the time, they not only cool out the overwrought, but have cars fixed again if necessary for nothing.

"All we want is for people to give us a chance," said the boss, John Koons Jr. "We're human; we're gonna make mistakes. But they're honest mistakes. And we try to fix them."

Connacher tells of a dentist - Dr. John Q. Respectable - who sat in the cool-out office one day in a suit and tie and calmly announced that he was about to drive his not-quite-fixed car through Connacher's window.

Then there was the man who felt cornered by Connacher, Hughes and another Koons official. He offered to take them all on.

Or the couple that decided to get a divorce on the spot, when the husband learned that the wife had authorized a valve job without consulting him.

Connacher said offers to fight are so common that he has developed a standard retort: "Wehn you want to start punching, start punching. Otherwise, get the hell out of here.

"Works evey time," said Connacher, with a smile and a shrug.

But it is the actual results on a sick car that make Hughes' and Connacher's jobs useful.

"There's nothing less effective than a fiery letter from a customer or a consumer advocate," said Alison Hughes. "The idea is to fix the car. We really want to do that."

"But that means inviting them to come back here, and they don't always want to do that," added Connacher.The result is that he and Hughes must "diplomatically tell people they're crazy" for not coming back.

That is tougher than it might be, because neither Hughes or Connacher has any psychological training.

"The only psychological experience I have is being alive for 30 years," Hughes said. Connacher's background of four years as a Fairfax County fireman and one as a management sales trainee does not seem a perfect path, either.

So the twosome often relies on Alison Hughes' femaleness to defuse situations.

Her presence will always "at least cut down on the cursing," said Connacher. And often, the mood of an encounter is transformed when Hughes replies to an irate question by quoting the reverse friction quotient of a hydraulic whatchamacallit.

"She knows her stuff," said John Connacher, and that is high tribute indeed in one of the world's most sexist businesses.