"I really hope that you will enjoy it because it has nothing to do with fashion," Ms. Tatou rather sheepishly told the audience, which was well-stocked with members of the fashion flock.

The film, opening in New York and Los Angeles on Sept. 25, follows Chanel from a bleak orphanage, to an attempted career as a bar singer, ending just at the cusp of her great fame. While fashion takes a backseat to drama in Ms. Fontaine's delicate and beautifully shot film, there are nods to the designer's style throughout, as when a young Coco notices the austere, angular white hats on a group of nuns or later stands awestruck in front of a group of fishermen, clad in blue-striped shirts.

And Ms. Tautou--gorgeous in a black and white dress by (of course) Chanel-was nothing if not fashionable on the red carpet. Her hair, cut boyishly short as usual, was worked up into a stunning pompadour. Still, she downplayed her own interest in fashion; she couldn't even say for sure if her outfit was from this season or not. 

"Everyone's always asking me for advice, which I never have," she said. "I think you should just wear what makes you happy and shows your personality."

Others were more inclined to show off.

British singer Estelle arrived wearing a, you guessed it, Chanel ensemble, complete with some glittering logo bling. She said she's been going strong all week in New York, visiting two to three shows a day, but was ready for a break. "I'm done," she said. "I think I'm going to a spa after this."

Was she tired of answering questions about Kanye West, her collaborator on the irrepressible single "American Boy"? "He's Kanye, that's all," she shrugged. "He's Kanye."

Model Hilary Rhoda remembered her first Chanel show for Karl Lagerfeld, but resisted comparing any emerging designers to the subject of the night's film. "Oh Chanel, I don't think they'll ever be another Chanel," Ms. Rhoda said. "She's very unique."

Others on the scene seemed relieved to be taking a break from a hectic week to sit in the dark for a few hours. Designer Erin Fetherston stopped to chat for a few moments, but others--including model Agyness Deyn, singer Ciara, and a very pregnant Adriana Lima--made a beeline for the theater. A few minutes before showtime, Ms. Lima reemerged to grab some popcorn and was already scarfing it down on her way back inside.

Actress Rachel Bilson (who could star in a biopic about Ms. Tautou, if anyone were to make one) was also there, making her way through the lobby. What was she wearing?

A little wearily she replied, pointing at her sheer black blouse. "Chanel."