Some 400 of 2,054 Buick dealers have enrolled in a program to update their stores to compete better against newer showrooms at rivals such as Lexus and Acura, General Motors Co. says.

Brian Sweeney, vice president-U.S. sales and service at Buick-GMC, says it will take up to 24 months to update those dealerships and require an investment of between $500,000 and $10 million at each one.

About 80 dealers already have renovated their facilities, he says, revealing for the first time details behind the upgrade movement.

The effort is part of a broader shakeup of GM's dealer network. As part of its bankruptcy, the auto maker submitted a plan to aggressively shrink its retail footprint but backed off after dealer groups and Washington lawmakers protested.

With fewer dealers, GM argued, those remaining could sell more cars every year and reinvest more of their profits into their facilities. Although the auto maker has retreated a bit from its initial plan, it still wants owners to agree to upgrades.

GM has the advantage of numbers over its foreign rivals, especially in rural areas, but much of its dealer network dates back to the 1950s. So while Buick's footprint is robust, the brand's image has changed significantly over the last 18 months, and many of the facilities selling its products have not kept pace.

“We're asking our dealers to take a fresh look at their franchise, just take a look,” Sweeney tells a group of GM employees at the auto maker's design center.

Sweeney and other executives are rallying employees to become ambassadors for Buick, as they present them with a deep-dive look here at the brand, its products and future plans.

Upgrades GM seeks include a new Buick-GMC showroom exterior facade, updated signage, a customer greeting station and customer lounge with items such as flat-screen televisions and wireless Internet access.

Other improvements sought by the auto maker are less costly. For example, Sweeney says Buick is asking dealership employees to “be professional and courteous (and) know the product.” It also wants them to welcome buyers within 60 seconds of entering the store and thank them for their business before they leave.

Craig Bierley, director-advertising and sales promotion at Buick-GMC, says dealers can count on better marketing support given GM's shrunken portfolio.

No longer will the auto maker “launch and leave” a product, Bierley promises. Launches, such as the upcoming '11 Regal sports sedan, will have a peak but continue over several years.

“We still think we are launching the Enclave and its 3 years old,” he says.

Buick also will continue to reposition itself under the concept of “unpretentious luxury” and the tagline “The New Class of World Class.”

For example, the brand has almost completely exited golf sponsorship, which a few years ago comprised 90% of its marketing, Bierley estimates. It now links itself with culinary and travel events and “know-on-the-go” technology such as sponsorship of the Wall Street Journal iPhone application.

And think of Buick alongside brands such as big-box stores Target and Costco, electronics giant Best Buy and upscale grocery store Whole Foods, Bierley says.

“Good quality at attainable prices,” he says.

As for the new Buick target customer, expect a married couple in their 40s with two children, a dual income of $130,000, graduate degrees, liberal-leaning political views and a physically fit lifestyle. That's a far cry from the current Buick buyer, averaging 65 years of age.