Whether they are buying a new car, having furniture reupholstered or shopping for a home, consumers have more buyer protection in Montgomery County than almost anywhere in the nation.

That is the prevailing wisdom among consumer officials familiar with the Montgomery County Office of Consumer Affairs, which enforces county consumer protection laws, including a law on deceptive and unconscionable trade practices, a condominium disclosure measure and laws regulating the automotive and electronic industries.

The agency obtained $1.4 million in refunds for consumers in 1984. It runs a telephone service to help consumers avoid mistakes while making purchases, and it compiles and distributes consumer information guides on a range of subjects, including home improvements, nursing homes and telephones. Its all-time best seller is "Crack the Codes," which tells how to decipher the dating codes on many food products.

When officials cannot resolve problems through mediation or arbitration, they file lawsuits and take other legal actions against offending businesses. In a 1983 case, Silver Spring Toyota, now doing business as Spencer Toyota, entered into an agreement with the agency to cease allegedly deceptive practices and to pay $10,000 for consumer education advertising written and controlled by the consumer office.

Montgomery County's consumer office is a "model for other agencies," said James J. Jones, the director of the Howard County Office of Consumer Affairs and the immediate past president of the National Association of Consumer Agency Administrators.

Much of the credit for the agency's success goes to Barbara B. Gregg, 50, a lawyer who has directed the office almost from the day it opened on Dec. 6, 1971. Gregg, who is paid $59,700 a year, selected and hired the 24-member staff and in general has handpicked the problems it tackles.

She initially had three temporary employes, a temporary office and an annual budget of about $100,000. Today, she has 24 full-time workers, a suite of pleasant rooms in the Stella B. Werner county office building in Rockville and an annual budget of more than $1 million.

While the Montgomery County office has been evolving into a model agency, others in the Washington area have run into problems. The consumer offices in Arlington and Alexandria were scaled down in the early 1980s as officials sought to curb expenses. The Fairfax County consumer office has expanded: it is about the same size as the Montgomery agency but less powerful.

Prince George's County has the power but not the stability -- there have been three directors in less than six years. The District of Columbia, meanwhile, has been torn by problems of reorganization.

Gregg's office draws its strength from the tough consumer protection laws enacted by Maryland and Montgomery County and from the expectations of local residents, who are among the nation's best educated and most affluent. Of Montgomery County residents 25 or older, 42.9 percent have four years or more of college, compared with 32.5 percent for the Washington area and 16.3 percent nationwide. The annual income for a Montgomery County household, based on the latest census information, is $28,987, compared with the Washington area average of $23,486 and the national average of $16,841.

"Look at the constituency you have in Montgomery County," said Jones. "You have an upper middle class that demands more in government services and good consumer protection. They are paying premium tax dollars and they expect premium services."

While such demands may have sustained the agency over the years, its direction has been largely in accord with Gregg's personal philosophy that there is a fundamental imbalance between the consumer and the business person and that steps should be taken to correct the situation. "Consumers have a difficult time becoming good shoppers, particularly when fraud is involved," she said.

Among the victories the office has won for consumers are:

* A local furniture store, European Interiors, went out of business three years ago, without returning furniture that had been brought in for upholstery and repair. Montgomery County investigators located 100 pieces of missing furniture, had it trucked to a local school for safekeeping and then traced the owners to let them know where to pick up their furniture, for an estimated savings to consumers of $21,000.

* A program on ethical advertising for new car dealers was initiated last year, and about 32 of the county's 42 dealers now participate in the voluntary program in which they agree to strict advertising guidelines. The program is believed to be the first of its kind.

* Anyone shopping for a used house may obtain a special "home buyer's questionnaire," a form filled out by the seller that provides information about the insulation in the home, problems with plumbing and other conditions.

Such results have enhanced Montgomery County's reputation. "If you rated the consumer offices around the country, Barbara Gregg's would rate in the top three, right up there with New York City and New Jersey," said Walter Dartland, the consumer advocate in Dade County, Fla. "Her office is among the elite."

Consumer advocate Ralph Nader said he has "heard good things" about Gregg's office but that, like all government consumer offices, it "is limited in what it does." The limitations are "across the board -- in budget, authority . . . and they don't do all that much investigative work either."

Others have complained that the office's telephone lines stay so busy that it is difficult to get through to ask a question or get help.

But on the whole, the agency is highly regarded.

Jones, who once worked in the office, described Gregg as a person "with a great deal of intelligence" and presence. "She doesn't make stupid verbal errors. She doesn't talk before her mind is engaged. If Barbara doesn't know, she will say she doesn't know and research it further."

Dartland, the Dade County advocate who has observed Gregg at professional meetings, said she "is aggressive in a nonoffensive way. She pushes. She is assertive. But she doesn't turn people off."

Gregg said her consumer philosophy was shaped by the work she did in the Neighborhood Legal Service office in Syracuse, N.Y., during the late 1960s. "I remember one major case attacking replevin -- that is when you are behind on your payments on your furniture, for instance, and they take your furniture without a hearing," she said.

The case, which Gregg won, advanced consumer rights in Syracuse and nationally because it helped establish the right of a consumer to a hearing prior to repossession of household goods, from jewelry to washing machines.

Gregg said her office has done well because it has had the support of public officials, legislation and a good staff. But one other reason is her ability to stay on top of emerging consumer problems. Thirteen years ago the focus was on the sale and repair of automobiles and television sets, she said. Today it is on housing, "particularly in the relationship between condominiums, homeowner associations and their board of directors," she said.

"People are into a whole new system of self-government. Some are doing it well because developers set it up properly and good people are elected, but others are having real trouble. And we are just starting to play a role in helping to close those kinds of disputes."