There's a new in-crowd in town, an elite group of politicians, professionals, hangers on and otherwise unnotables, cruising through the District and proudly displaying their membership cards - one or more of the infamously prestigious low-digit D.C. auto tags.

It is a trendy group, many of them given to sports cars and foreign jobs, an inner-society of men and women who earned their stripes by being on the winning sides in last year's political wars. It is a group in which the lower the number the bigger the boast, and a club whose principal godfathers are the two new men at the top of city government - Mayor Marion Barry and City Council Chairman Arrington Dixon.

Effi Barry, the mayor's wife, is the undisputed queen bee of the club, for she has the coveted No. 1 tag prominently displayed on her 1973 Volkswagen - no small accomplishment for a woman who came to this city only four years ago.

Robert B. Washington Jr., the lobbying lawyer who dabbles heavily in city politics and last year could only manage a number in the upper 20s, is now No. 2. Washington didn't even support Barry for mayor in last year's crucial Democratic primary, but he did support Dixon, who apparently remembers his friends.

Tag No. 3 now belongs to Elijah B. Rogers, the new city administrator with the silver-gray Alfa Romeo convertible. That tag used to belong to Rogers' predecessor, the feisty Julian R. Dugas.

Banished from the 5th floor of the District Building when Walter E. Washington was defeated and banished from District government when Barry took over, Dugas has now been banished from the low tag list, left to drive around with a six-digit tag like most other people in the city.

Gone from the club are two of its most prominent members. Daisy P. Moore, No. 4, the wife of the rambunctious former Council member Douglas E. Moore, lost out when her husband challenged Dixon and lost.

The owner of tag No. 5 used to be easy to find. "The mayor is No. 1, the city administrator is No. 3 and I'm No. 5," John R. Risher Jr., the strait-laced aristocratic former corporation counsel in Washington's administration, once explained. Now Risher is who-knows-what-number, and his old tag, like Daisy Moore's, is on the shelf waiting for someone else.

With the same compassion and political tact it used in dismantling Washington's bureaucratic empire, the Barry administration has purged the upper ranks of The Club of Washington holdovers.

Joseph P. Yeldell, the one-time flamboyant Washington confidant who used to have tag No. 11 on his Lincoln, has been demoted to No. 490.

Lawyer Charles T. Duncan used to be the undisputed attorney general of the club. But he no longer advises the mayor on legal problems. Herbert O. Reid does that. As evidence of his new position, Reid has No. 16 - Duncan's old tag.

Former police cheif Jerry V. Wilson lost tag No. 29 to C&P Telephone executive Delano E. Lewis, Barry's transition chief. Retired D.C. Superior Court Judge Robert H. Campbell, who left the bench under the cloud of a U.S. Attorney's investigation, has also left the upper rank of The Club's hierarchy. Campbell, a close friend of Dugas, gave up two tags - No. 39 to Barry inaugural director Thornell Page and No. 98 to Barry's principal image maker, advertising executive David Abramson. Campbell was rassigned No. 654.

Garfinckel's vice president Joseph B. Carter, who headed Barry's strategy committee and lent his establishment, church-connected reputation to Barry's image polishing effort, got tag No. 11. Lawyer Max Berry, treasurer of the Barry campaign, got No. 20.

One of the mayor's old poker partners and close friends, James Palmer, senior chief deputy of the U.S. Marshal's office here, is No. 21. Lorraine Whitlock, the workhorse of the Barry campaign in Ward 7 - where the mayor is likely to buy a home - is No. 25. Gilbert and Ann Kinney - she once raised $60,000 for the mayor in one two-hour luncheon - have been given No. 32.

Barry also introduced into The Membership Frank Kameny, the activist patriarch of the local gay community, who was given No. 433. Gay voters were key contributors to Barry's victory.

In the administration itself, the jostling for tags was sometimes intense. For example, special assistant Lillian Adkins Sedgwick, who during the campaign had dared to champion Barry's cause in the hostile political lands of the upper 16th Street corridor, was upset because she only got tag No. 76.

Sedgwick was saved by fellow special assistant Warren Graves. He declined the offer of tag No. 38 and gave it instead to Sedgwick.

In seeking to expand his political base, Barry assigned or renewed more than a dozen low digit tags to ministers, including the influential Bishop Walter (Sweet Daddy) McCullough of the United House of Prayer for All People, who has supported Walter Washington in last year's campaign.

Bishop Smallwood E. Williams of Bibleway Church, who initially opposed Barry but later endorsed him when it was clear Barry would win, was given tag No. 733. That made Williams one of only two individuals on the list to have three of the precious tags.

The other envied member of The Club's 3-tag hierarchy is entrepreneur Leonard Manning, an old friend of Council Chairman Dixon, who, among other things, encouraged Dixon to make the former Sharon Pratt his wife.