Bye-bye, indeed, Miss American Pie. If General Motors has its way, you won’t be driving your Chevy to the levee ever again.

On Tuesday, G.M. sent a memo to Chevrolet employees at its Detroit headquarters, promoting the importance of “consistency” for the brand, which was the nation’s best-selling line of cars and trucks for more than half a century after World War II.

And one way to present a consistent brand message, the memo suggested, is to stop saying “Chevy,” though the word is one of the world’s best-known, longest-lived product nicknames.

“We’d ask that whether you’re talking to a dealer, reviewing dealer advertising, or speaking with friends and family, that you communicate our brand as Chevrolet moving forward,” said the memo, which was signed by Alan Batey, vice president for Chevrolet sales and service, and Jim Campbell, the G.M. division’s vice president for marketing.

“When you look at the most recognized brands throughout the world, such as Coke or Apple for instance, one of the things they all focus on is the consistency of their branding,” the memo said. “Why is this consistency so important? The more consistent a brand becomes, the more prominent and recognizable it is with the consumer.”

Although the memo cites Coke, it does not note that Coke is shorthand for Coca-Cola — or that Apple is not commonly used in reference to its products, which are known simply as iPads, iPhones and MacBooks.

One expert on branding said G.M.’s effort ran counter to a trend in which corporate names had become more casual. The consultant, Paul Worthington, head of strategy for Wolff Olins, a brand consulting company, noted that FedEx had replaced Federal Express, KFC had supplanted Kentucky Fried Chicken and “even RadioShack has evolved into the Shack.”

Regardless, if Chevrolet plans to put the Chevy genie back in the bottle, the task could prove harder than climbing out of bankruptcy.

As of Wednesday night, the word Chevy appeared dozens of times on Chevrolet’s Web site, chevrolet.com, including a banner on the home page that said, “Over 1,000 people a day switch to Chevy.” One of the dropdown menus was “Experience Chevy.” On Facebook, brand pages include Chevy Camaro, Chevy Silverado and Team Chevy.

If taken to its logical conclusion, Chevrolet would presumably need to ask Jeff Gordon, the four-time Nascar Sprint Cup champion who currently races a Chevrolet Impala, to change the Web site address — jeffgordonchevy.com — for his dealership in Wilmington, N.C.

And what about rolling back the popular culture references to Chevy? Elton John, Bob Seger, Mötley Crüe and the Beastie Boys have all sung about Chevy, and hip-hop artists rap about “Chevy Ridin’ High” or “Ridin’ in My Chevy.”

There are also a good many auto enthusiasts who have "Chevy" tattooed onto various body parts. Some probably have a Chevy II or two tucked in their garages.

“It’s a ’Vette, it’s a Caddy, it’s a Chevy,” said Dick Guldstrand, a long-time racer who has been inducted into the Corvette Hall of Fame. He noted that the brand was named for Louis Chevrolet, a race driver of the early 20th century.

“Once it became an American icon, America took it away from G.M.,” said Mr. Guldstrand, 83. “They made it a Chevy. You’re doing a disservice to all the people by telling them not to call it a Chevy.”

In 2006, Chevrolet updated a series of popular commercials with the tagline “Baseball, hot dogs, apple pie and Chevrolet," which noted how the brand was woven into the fabric of American culture.

The commercial juxtaposed imagery of past baseball greats with modern ones. And at the end, the narrator says, “Apparently, baseball’s changed a little over the years, but not America’s love of the game — or love for Chevy.”

So why make the change now? G.M. wasn't saying, but the memo came after several major marketing moves. The memo was provided to The Times by the disbelieving recipient of a copy.

In April, Chevrolet dismissed its long-time ad agency, Campbell-Ewald, which over several decades had created such memorable slogans as "See the U.S.A. in your Chevrolet," "Like a rock" and "The heartbeat of America." The account went to Publicis USA, but only for a month. In May, Joel Ewanick was hired from Nissan to head United States marketing for G.M. Shortly after settling into his position, Mr. Ewanick switched the Chevrolet advertising account again, this time to Goodby, Silverstein & Partners.

Klaus-Peter Martin, a G.M. spokesman, confirmed the memo. "We're going to use Chevrolet instead of Chevy going forward in our communications," he said in a telephone interview, and linked the change to the move to Goodby.

Mr. Worthington, the branding expert, said Chevrolet seemed unclear what the brand stood for. "So what it would appear they are trying to do, by centralizing to a single formal name, is to try to get some focus as to what that brand stands for, and get that out into the marketplace, which makes a lot of sense."

Ultimately, he said, consumers "will call you whatever they want to call you."

But not Chevrolet staff members. A postscript to the memo says a sort of cuss jar - a plastic "Chevy" can - has been placed in the hallway. "Every time someone uses ‘Chevy' rather than Chevrolet," the note said, the employee is expected to put a quarter in the can.

The proceeds are to be spent on "a team building activity."

Presumably, that would not include nachos for the staff at Chevy's.

By RICHARD S. CHANG