One of Washington's rarer events is the opening of a new auto dealership. Area dealers overwhelmingly prefer the suburbs to the city for selling their machines.

Of the estimated 165 auto dealers in metropolitan Washington, only nine are in the District of Columbia. And the nine include the newest arrival, Connecticut Avenue Datsun, the District's first dealership since 1979.

Connecticut Avenue Datsun also is the latest of 11 Washington area dealerships operated by Rosenthal Automotive Organization.

The new Rosenthal shop is situated at 4221 Connecticut Ave. NW in the same building where Flood Pontiac Co. once sold Pontiacs (General Motors Corp.), Rolls-Royces, and "taxicab" cars made by Checker Motors Corp. of Kalamazoo, Mich. Flood was washed away by the recession in 1980, two years before Checker Motors went under.

Many District auto dealers have gone the way of Flood, which is why the opening of the Rosenthal shop "is a real significant sign" of renewed dealer confidence in the District, said Gerard N. Murphy, executive vice president of the Automotive Trade Association-National Capital Area.

"There was a time when all of the dealers were in D.C., when our association used to be called the Washington Automotive Trade Association," Murphy said of his organization, founded in 1917. But the association changed to its current name in 1954 to reflect the reality "that more and more dealers were moving to the suburbs," Murphy said.

Still, there were as many as 70 auto dealers in the District in 1960, said Murphy. But he said modern dealership demands for greater floor space, and dealer flight from comparatively higher District taxes accelerated the drive to the suburbs. Also, "There was the question of plant security. Security costs were higher in the District than in the suburbs," Murphy said.

But the few dealers who stayed are doing well. And indications are that Rosenthal will do well in the District, too, Murphy said.

Rosenthal has a better-than-even chance of living up to Murphy's prediction, according to Norfolk regional officials of Nissan Motor Co., Ltd., the Japan-based manufacturer of Datsun cars and trucks. Nissan officials said Rosenthal, through its first Datsun shop in Vienna near Tyson's Corner, already was the largest-volume dealer of Datsuns in the Washington area.

"Business is very promising," said Jay Peterfreund, general manager of Connecticut Avenue Datsun. Since opening last month, the new dealership has received "a good customer response," Peterfreund said. He declined to give specific sales numbers.

Peterfreund said Connecticut Avenue Datsun's location in a neighborhood "that attracts many upper-middle-income, professional people" is paying off in a brisk movement of expensive Datsun models such as the Maxima. "But we're selling trucks, too," he said, adding that the new shop is having no trouble moving "a full line of models."

Datsun is the second-largest importer of cars to the United States, accounting for 221,500, or 6.1 percent, of all of the cars sold in this country between Jan. 1 and May 31 of this year. Toyota Motor Corp. is the largest importer, selling 223,500 cars so far this year, or 6.2 percent of the market.