Yves Montand arrived in a sleek, Black Eagle Jeep. Jodie Foster stood at his side, with a new punk hairdo, and as the paparazzi flashed away, starlet Michelle Johnson squealed, ''Oh my dear, isn't it so wonderful.''
The occasion was the opening of the 10th annual American Film Festival last weekend. It was glitzy and glamorous, yes even wonderful - and not at all in the image of the Deauville of old, that upper-crust channel resort of hushed voices and studied elegance.
To be sure, Europe's affluent continue to gather here in the late summer just as they have ever since the town was founded in 1861 by the Duc de Morny, half brother of Emperor Napoleon III. This August, such aristocratic jet-setters as Baron Guy de Rothschild, Britain's Lord Spencer-Churchill, and Greek shipping magnate Stavros Niarchos came to watch their horses gallop down the backstretch at La Touques, or to whack a polo ball, or to play banco.
''We don't want everybody's business,'' says tourist director Jean-Pierre Reyns, ''only the cream of the cream.''
Still, leisurely, aristocratic elegance is just not so leisurely or elegant these days. The crowds are massive:
In August the town's population swelled from 5,500 to some 50,000 - all of whom seemed to be at the beach at the same time. The idea was to be seen strutting like a peacock down the boardwalks, which are set with fancy cafes and boutiques.
''I won't even go into town anymore,'' says Baron de Rothschild, taking tea and crumpets at his stately 15th-century estate down the road. ''There's just no class anymore.''
Tourist director Reynes would disagree with the baron's assessment, but he admits Deauville has been forced to change with the times. In his view, Deauville now sells a different type of class.
''Before, the industrialists, princes, and the kings came here,'' he explains. ''Now, it's the new aristocracy, the managers, the doctors, the lawyers, and often, they come from Paris just for the weekend.''
The changes date from World War II. Following the war, Deauville's elegance became equated with staidness, and the town fell into a slumber, eclipsed by such Mediterranean sun spots as St. Tropez and Cannes.
This abruptly changed in 1962 when Michel d'Ornano became mayor. Mr. D'Ornano revived the town by modernizing its facilities and its marketing.
He promoted the first direct train service from the capital as well as construction of a Paris-Normandy highway. Now only a two-hour journey from Paris , Deauville became accessible for a fun weekend.
To accommodate the flocks of Parisians, many of Deauville's run-down, 19 th-century villas were replaced with modern apartment clusters. The luxurious Royal and Normandy hotels were revamped, and indoor swimming pools and covered tennis courts were built, all so the resort could extend its short season.
The new strategy was capped in 1975 by instituting the American Film Festival. Before, Labor Day signaled the end of Deauville's summer festivities. Now, some 5,000 tourists jam the town to see the films and peek at the stars.
''Deauville needed to become a cultural as well as social happening,'' says festival director Andre Halimi. ''The films add that extra ingredient.''
As desired, the film festival brought Deauville added clientele - and put the town on the front line of a first-class cultural battle.
Two summers ago Socialist Culture Minister Jack Lang called for ''a crusade'' against American ''cultural and financial imperialism,'' and conspicuously boycotted the film festival here.
Mr. Halimi responded aggressively. ''What do they want, a Togo film festival? ,'' he asked at the time. ''No one would come. Cinema is an American invention, and American film should be better, not less, known here.''
Judging from the Deauville scene this year, the Halimi counterpunch seems to have carried the day: American films, and America in general, seem more popular than ever. Even before the festival opened, the town's ''in'' film was ''Romancing the Stone.'' Many stores feature ''American-style'' goods. Many cafes have been transformed into ''burger bars.'' American flags hang everywhere.
''It's become part of our own culture,'' exclaims singer Montand. ''It's part of us, we love it, so why fight it.''
Festival director Halimi nodded his head in agreement, adding, ''Everybody has forgotten what Lang said.'' At that moment, as though to prove Halimi's point, Jacques Attali, personal adviser to President Mitterrand, strolled into the hotel lobby and complimented him on the festival and the films.
The festival will climax Saturday evening with the French premiere of George Lucas's ''Indiana Jones and the Temple of Doom.'' In the past few years, the French have become infatuated with many things American, even such previously unfashionable political ideas as liberalism, tax-cutting, and entrepreneurship. But above all, America remains the great adventure.
''The spectacle, the epics, that's what we love,'' says Halimi. ''Only America makes it.''
Already, Halimi says his American Film Festival is Europe's second great cinema event, just behind the Cannes festival. Many film professionals here would rank the Venice festival higher, but no one questions that Deauville is gaining in stature.
To accommodate the overflow crowds, Halimi soon hopes to begin construction on a 2,000-seat cinema hall. Meanwhile, Deauville keeps working on its image. Tourist director Reyns bemoans an influx of low-class day-trippers this summer whose uncouth manner annoyed the moneyed professionals. He promises to keep such ''undesirables'' out next year by increasing parking and parasol charges.
Definitely in, though, are wealthy foreign tourists, especially Americans. In recent years, Reyns has toured the US promoting Deauville.
At first, he says, most Americans thought he represented a Florida resort. But thanks to promotion and the favorable exchange rate for the dollar, ''At least Americans now know Deauville is somewhere in France.''
The proof: American tourism here is booming. Reyns reports that 15 percent more foreigners visited the town this year and that Americans now rank first in numbers, representing some 11 percent of the total.
The message, Reyns says, is also clear:
''We love America.''