Buoyed by record 1985 sales and the promise of a comparable performance in 1986, an estimated 18,000 auto dealers are arriving here this weekend for what is being billed as the biggest convention in the 69-year history of the National Automobile Dealers' Association.

Dealers of imported and domestic vehicles sold 15.7 million cars and trucks in the United States last year, racking up total "best-ever" annual sales of $260 billion.

That means that average sales for each of the nation's estimated 25,000 dealers in 1985 amounted to $10.5 million, surpassing last year's record of $9.3 million.

NADA's 1986 convention, as a result, has taken on the air of a grand party in a city that knows how to throw one.

But beneath the fast-paced socializing in the hotels and big-bucks spending on the convention's exhibition floor, there is a lot of grumbling about a new get-tough policy among domestic auto makers that some dealers say could put them out of business.

The manufacturers' new approach is best characterized by what they and the dealers call "consumer satisfaction" and by the "consumer satisfaction index" surveys that foreign and domestic car companies are using to rate their dealers' performance in the marketplace.

This is a very important matter, according to the dealers and Jack Mayne, editor of California-based Automotive Age, a national, independent dealer business magazine.

Although the CSI surveys are "an important and welcome step in improving the overall car business, there is a lot of fear among dealers that the manufacturers are going to use the survey results to just club the dealers over the head," Mayne said.

Small dealers and those who handle domestic cars are particularly worried. The small dealers often do not have the capital to meet growing consumer needs such as computerized repair facilities, while domestic-car dealers of all sizes fear they are in a no-win situation with customers because they often are handling products generally perceived as being inferior to imports, Mayne and several dealers interviewed here said.

These dealers fear that manufacturers will use consumer satisfaction ratings as an excuse to withdraw franchises in areas where the companies want to consolidate or even pull out. They worry that, at a minimum, the companies will deprive them of an important new product such as the 1986 Ford Motor Co. Taurus or Sable or General Motors Corp.'s planned Saturn car, according to some leading dealers here.

A number of domestic dealers are complaining that their manufacturers are using CSI results to punish them for crimes that they did not commit.

"The American manufacturers are trying to correct their problems by putting the monkey on our back," said James B. Woulfe, president-elect of the 20,000-member NADA group.

About 84 percent of NADA's members sell domestic cars and trucks, but many of those same dealers also sell imports. An estimated 15.4 percent of the association's members sell imports exclusively.

Native U.S. car companies "have the finest engineers and designers in the world, but it seems that they can't put out a new car line without problems," Woulfe said in an interview.

But in tabulating CSI results, which are calculated and analyzed differently by each manufacturer, domestic auto makers often blame their dealers for problems that are inherent in the product itself, Woulfe said.

Manufacturers disagree.

"General Motors does not see itself as doing that at all," said James Vorhes, GM's vice president for consumer relations.

GM is taking a tougher stand on dealer performance because it does affect overall consumer response to the company's products, Vorhes said, but he added that GM is working closely with its dealers to develop programs that would improve consumer satisfaction without unduly burdening dealerships.

"We see our dealer organization as being part of a complete consumer satisfaction system," Vorhes said. "When something goes wrong, consumers don't blame the dealer or the manufacturer. They blame the whole system."

Something "goes wrong" two out of every three times a new car is delivered to a buyer, according to a recent survey of new-car buyers conducted by Denver-based Consumer Contact Corp.

"Nearly two-thirds of all new cars are delivered to customers with mechanical problems. . . . The problem areas reported most frequently are engine components, electrical systems, and general squeaks and leaks," said a summary of the survey published by NADA.

The Consumer Contact survey shows that "all dealer problems are definitely not dealer-caused," said Sharon Dixon, president of Consumer Contact.

Relationships between domestic dealers and their manufacturers historically have been rocky affairs. Dealers, for example, often have accused auto makers of forcing them to accept unwanted products -- or of not producing enough hot-selling models to satisfy consumer demand.

Manufacturers have argued that their dealers often form the weakest link in the quality chain. That alleged failing, in recent years, has contributed mightily to a decline in consumer satisfaction with domestic products, auto makers say.

A recent survey by California-based J. D. Power & Associates, a national automotive market research firm, supports the auto consumer and industry perception that domestic makes generally are held in lower esteem than imports.

The Power results are based on an analysis of consumer attitudes about their new cars and their dealers 12 to 14 months after purchase. In the 1985 Power survey, which involved 1984 cars, only one domestic finished in the top 10 in consumer satisfaction. That one was a Ford-made Lincoln, and it finished 10th.

John J. Pohanka, who owns a chain of domestic and import dealerships in the Washington metropolitan area, agreed that domestic cars tend to get more complaints than the imports. But he said that the complaints do not necessarily mean that the domestic products are inferior.

"The domestic car has tended to be more complex than the import because it has more computers and electronics," Pohanka said. "But that's changing because more and more computerization is coming into the imports."

More complexity and computerization generally means more difficulty in repairing cars; and more difficulty in repairing cars often means lower consumer satisfaction ratings, said Pohanka, who is a past president of NADA.

As a result, "emotions tend to run high" among dealers and auto makers, Pohanka said. "None of us likes to be criticized. But consumer satisfaction is a very important issue, and we've both got to do something about it if we want to keep customers."

Pohanka said that dealers and auto makers are taking a positive step together to solve the problem by improving training for mechanics and other service workers at dealerships.

"That means we're trying to do a better job of fixing cars and customers," Pohanka said. "The cars today are more complex. Sometimes you run into situations where there is no immediate fix.

"But a dealer has to be in a position to explain that to a customer in a way that will show the customer that his business really matters."

The tension between dealers and auto makers is a natural outgrowth of the drive to sell cars and trucks in volume in order to cover rapidly escalating costs, while maintaining customer loyalty, Pohanka said.

"It's basically the same challenge facing any business," Pohanka said. "But instead of pointing fingers at each other, we've got to find a way to meet that challenge if we want to stay in business."