Relatively affluent suburban housewives, in significant number, still drive to downtown Washington on shopping trips.

They park their cars in a garage behind the Washington Hotel and walk across F Street NW to the main store of a business started in 1905 by Julius Garfinckel. Often, these shoppers remain inside for hours. They relax for lunch at the retail firm's restaurant.

William C. Detwiler, president of the Garfinckel specialty stores here, said last week that the suburban shoppers are regular customers "who want the benefits of the wider selection downtown." The store also attracts a good business from people who work in the city and jam the store from 11:30 a.m. to 1:30 p.m. most weekdays.

Garfinckel's also attracts individuals who live in the District to its downtown store, including a steadily increasing number of affluent and middle-class blacks.

It adds up to a business of large volume and good profits, the sort of environment that makes entrepreneurs happy. According to Detwiler, it adds up to a tribute to Garfickel's and the factors he believes attract people to the downtown store - "obvious quality" of merchandise, "good taste," "value" and, "by no means last, service in all aspects, from selling to delivery."

The main selling floor of Garfinckel's today reflects a non-trendy atmosphere that makes the specialty store distinctive in an era of mirrors, chrome and splashy colors. Garfinckel's has wider aisler than many stores. It polished wood counters are unclutered.

"Under no circumstances do we intend to be a carbon copy of Bloomingdale's, the New York department store that recently opened two colorful stores here. "The worst thing we could do would be to attempts to redo our first floor. You develop your own strengths, not imitate someone else's," Detwiler added.

What Garfinckel's offers is a "feel you want," not confusion, the retail executive said on a walking tour of the big downtown store, where the sixth floor has just been redecorated with bright paint and new carpets for the juniors and contemporary women's departments. Additional renovations are planned this year as Garfinckel's develops special boutiques for certain product lines, but the emphasis is on evolution and not revolution in merchandise presentation.

When shoppers walk out of Garfinckel's, many go back to their cars and head of home. A few cross 14th Street and walk down the F Street Mall toward the main stores of Woodward & Lothrop and the Hecht Co., along a shopping strip that in earlier decades was the premiere retail center of the federal city.

Those who do expand their trips beyond Garfinckel's walk through a shopping center that has been fighting for survival since the 1960s, when regional malls began to attract more of metropolitan Washington's business, when urban rioting convinced some area residents they never should come downtown, and when subway construction and auto traffic jams meant wasted time and inconvenience.

It is easy to be pessimistic about the future of downtown shopping, even if there are three big stores remaining with a wider selection of merchandise than any other area department stores.

Kann's and Lansburgh's, two other large department stores, failed and closed inrecent years despite often distinctive goods; it generally was conceded, for example, that Lansburgh's downtown had the best selection of fabrics in the entire area. Safeway Stores has closed its unique international food center.

Some smaller merchants either have failed or move away. Other stores are planning to close their doors, such as the leading jewelry firm of Chas, Schwartz & Son, at 1313 F St., which plans to join Neiman Marcus of Dallas at the Mazza Gallerie on upper Wisconsin Avenue later this year.

There is a honky-tonk atmosphere and there are racks or tables of cheap merchandise along parts of F Street today that don't measure up to the clean environment of a Landover Mall or the sleek sophistication of new White Flint. Overall, downtown sales have been sliding downhill gradually for a decade.

However, ther now are signs that the worst years are behind the merchants who have remained along F and G streets and the adjacent side streets. People like jeweler Schwartz are being told by some of their friends that moving away now is a mistake.

"We feel very positive about downtown," said Garfinckel's Detwiller. "We're excited by the prospects of Pennyslvania Avenue redevelopment, and revival of the Willard Hotel can't do anything but help downtown. The current and past management have worked very hard to maintain this plant." He said also that the necessary energy shortages in future years will accelerate the shift toward central cities as a place for living and shopping.

"It's not all gloom and doom although there are some serious problems," he added. The major problem in recent months for downtown retailers, for example, has been an evident cutback in spending by relatively low-income consumers, whose incomes have been squeezed.

Overlooked by the pessimists, however, in the case of Washington, is the drawing power of the three remaining large downtown stores - Garfinckel's, Woodies and Hecht's. Last year was not a growth period for most retailers here, a typical experience during election campaigns and a subsequent shift in national administrations.

Despite a surge of business during the Christmas season, combined sales of the three big downtown stores for all of 1976 were down 2 per cent from the previous year, according to the U.S. Commerce Department.

And yet, the total sales of these three stores alone for 1976 were $94 million - a figure not much less than the $100-$150 million volume of the most successful regional malls that have four major stores and more than 75 smaller stores and services. Moreover, despite the ills apparent downtown, Washington's central city remains the largest retail shopping center in the metropolitan area - with annual sales estimated at more than $400 million.

Owners of Woodies, Hecht's and Garfinckel's obviously plan to stay downtown. Locally owned Woodies, for example, has budgeted hundreds of thousands of dollars for a complete renovation downtown that will be completed by 1980. President Edwin K. Hoffman said his store has benefitted materially from a subway stop underneath his store that is bound to bring even more business when the mass transit system is expanded this summer.

At the Hecht Co., owned by May Department Stores of St. Louis, renovations have been completed over the last several years and are continuing.

With the expectation that a convention center soon will be started in the Mt. Vernon Square area to the north of downtown and federal funding for Pennsylvania Avenue redevelopment, officials of the three major stores have projected nothing but increased sales downtown, once construction at the Hecht Co. end of the street is completed.

Smaller merchants, meanwhile, joined with the District government last week to begin a facelifting program sponsored by Park and Shop, a group of 150 retailers and professionals organized two decades ago to promote downtown business. The city said it will paint exteriors of buildings it owns in the area, some of which are scheduled for demolition in future years. Private landowners are being encouraged to do refurbishing on their own, and Park and Shop hopes 150 or 200 buildings will be involved in the project.

Obviously, a major goals of the downtown retailers is to convince shoppers at Woodies, Hecht's and Garfinckel's to browse more generally throughout the retail center.

The optimism evident in capital outlays for a facelifts to buildings or major interior rebuilding is not being duplicated in all other cities. In Detroit, many major retailers have closed or will close in coming months. In Baltimore, downtown department store sales plummeted in 1976 by 9 per cent to only $53 million (for five large stores vs. more than $90 million at three in D.C.). Hochschild Kohn will close its downtown store in Baltimore this summer, and Stewart & Co. has warned it may do the same if an ambitious downtown rebuilding project isn't started soon.

When Washingtonians look back in future years at the revivals of their downtown, which now appears to have started, much of the credit will go to the three major stores that stayed - because it was good business to do so and not out of charity.

Garfinckel's is a good example. Every year since downtown riots in 1968, rumors have swept the F Street retail community that Garfinckel's is about to pull out. The reaction to these rumors generally has been one of fear among smaller store owners and managers. If retailer with the purchasing power and economic muscle of a national retail chain couldn't survive, how could they?

In fact, said Detwiller last week, his firm never conteplated closing its F Street flagship, with 170,000 square feet of selling space and the largest volume of sales for any store in the Garfinckel division of Garfinckel, Brooks Brothers, Miller & Rhoads, Inc.

Like managers at Woodies and Hecht's, Detwiler refused to be specific about downtown sales in terms of dollar figures. General policy is not to divulge such data for any single store. He said only that the "performance of the downtown store is not a fluke," that downtown sales have increased each year at least since 1971 and that 1976 was a record year.

The rate of sales gain downtown parrallels within one percentage point the overall volume growth of the national Garfinckel, Brooks Brothers chain, he said. In 1976, sales of the parent firm were up 2.3 per cent (the fourth-quarter sales rise exceeded 15 per cent).

Retail sources said that of the three big downtown stores, Garfinckel's has the smallest portion of annual sales because it is a specialty store that attracts a more limited and generally more affluent market than Woodies or Hecht's. Volume at the Garfinckel store downtown has been estimated at between $15 million and $20 million out of overall Garfinckel division annual sales exceeding $50 million.

"It certainly is worth saving F Street," Detwiler concluded.

At the same time, Garfinckel's is spending more than a quarter-million dollars to renovate its Spring Valley store in Northwest Washington and will add some new and expanded lines of cosmetics, accessories ans ready-to-wear. Other sites are being studied for new stores of various sizes.