American Motors Corp. dealers in the Washington area, long a struggling lot, are smiling nowadays.

The reason is a 1.4-liter, Franco-American, front-wheel-drive passenger car, appropriately named the Alliance.

To say the car is selling well is profound understatement. It is, in the words of Tyson's AMC/Jeep/Renault dealer Hal Nebel, "enjoying more public acceptance than any car I've ever sold. And I've been in this business for nearly 30 years."

Some might regard that as hyperbole. But the figures rolling in from around the Washington area and the nation justify the enthusiasm.

Consider:

* Washington area AMC/Jeep/Renault sales for November increased 148 percent over the year-ago period, with the Alliance accounting for the bulk of that increase, according to AMC Washington Sales Zone officials.

* Without rebates or similar gimmicks, AMC has registered national sales gains each month since its Sept. 22 introduction of the Alliance. For example, AMC sold 13,461 cars last month in 24 selling days, a 37 percent increase over 9,448 cars sold in 25 selling days in November 1981. The Alliance accounted for 7,590 of the AMC/Jeep/Renault cars sold nationally last month.

* AMC, the fourth-largest U.S. automaker (1.4 percent of the domestic auto market), plans to build 12,000 cars this month, a 278 percent increase over 3,175 cars the company produced in December 1981. Other domestic automakers, notably General Motors Corp., the largest, have been cutting back production in a recessionary market.

"We've been waiting for this kind of thing," Nebel said, adding that his dealership has sold 100 Alliances since Sept. 22. "We have a well-trained staff, but this car practically is selling itself," he said.

The Alliance is the American version of the R9, designed and produced in France by Regie Nationale des Usines Renault, a partner with AMC since 1979. The Alliance model -- designed to take away market share from subcompacts such as Honda Civics, Volkswagen Rabbits, GM Chevrolet Chevettes, and Ford Motor Co. Escorts -- is built in Kenosha, Wis.

AMC dealers here and elsewhere say the Alliance's best-selling points are its European styling, its mileage -- which has been estimated at 52 miles per gallon by the Environmental Protection Agency -- and its price, which ranges from $5,595 for a basic two-door model to $7,470 for a deluxe four-door edition.

The car is selling so well that "there's some cannibalization of our sales" on other lines, said AMC spokesman John McCandless. For example, the shift to the Alliance has all but wiped out sales of AMC's aging, rear-wheel-drive Spirit, 587 of which were sold nationally in November. McCandless said 90 percent of the Alliance's customers are first-time AMC car-buyers.