Washington-area independent auto repair shops are doing a better job of satisfying their customers than are new-car dealerships, according to a survey of local auto repair operations released yesterday.

Independent repair shops generally do a better job and charge lower prices than their manufacturer-franchised competitors, according to the Checkbook magazine survey published by the Center for the Study of Services, a Washington-based consumer information and research group.

Representatives of area new-car dealers immediately challenged the report, saying that it did not take into consideration the full range of services offered by dealers.

"Our people typically have more certified mechanics, which means that they have better mechanics than most nondealers," said Gerard N. Murphy, president of the Automotive Trade Association of the National Capital Area. "I guess you can do anything with numbers, but our experience is that we do a better job of taking care of the total car.".

The Checkbook report was based on responses from approximately 10,000 consumers who evaluated job performance and pricing policies at 353 local repair shops. Possible overall evaluations were "inferior," "adequate" or "superior." Of the 353 shops studied, 42 were rated "adequate" or "superior" for "doing work properly" by at least 95 percent of their surveyed customers. Thirty-seven shops were rated as "inferior" in the same category by at least 50 percent of their customers in the survey.

Most of the shops receiving the highest consumer ratings were independents. Most of those receiving the lowest marks were new-car dealers. For example, 87 percent of the surveyed customers said that independents did acceptable work -- "adequate" to "superior." By comparison, 68 percent gave satisfactory ratings to dealers. Dealers had a higher consumer complaint rate, 77 percent versus 31 percent for independents.

The Checkbook report also challenged Murphy's assertion that the presence of more certified mechanics in a repair shop means better service. Forty-five percent of the dealers had certified mechanics, versus 39 percent of the independents in the survey.

Certification of auto mechanics usually comes through the Washington-based National Institute for Automotive Service Excellence. Since its founding by auto industry representatives and consumer groups 13 years ago, ASE has been giving rigid tests to mechanics willing to participate in a voluntary certification program.

There are 180,000 ASE-certified mechanics in the United States. But the organization has certified 300,000 mechanics since its beginning. The problem is that ASE certification lasts five years, and some auto repair businesses continue to tell customers that their mechanics are ASE-certified even though the certification has expired, ASE President Ronald H. Weiner said.

Other repair shops might fail to tell customers that their mechanics are ASE-certified in only one area of automotive repair -- such as brakes, for example -- Weiner said.

"You also have to keep in mind that the certified technician is one building block in a rather complex puzzle," Weiner said. "You also have consumer expectations, pricing policies and management policies" that can affect consumer satisfaction.

On pricing policies, too, the independents generally did better than their dealership competition, the Checkbook report said. The average hourly rate at surveyed local dealers was $36.94, compared with $32.54 for independents, the report said.

"But price tells you nothing about quality," the report said in comments about the whole field of surveyed shops. "For example, of the 42 shops rated 'average' or 'superior' by 95 percent or more of their surveyed customers, 21 were among the lowest-priced one-fifth of surveyed shops."