General Motors Corp. can do without its Saab brand, but the same might not be said for Pontiac, says Jeffrey Anderson, director-consulting and analytics for data firm Experian Automotive.

“Saab wasn't bringing a lot to GM, but Pontiac, as well as Saturn, are as big as some stand-alone auto makers,” he tells Ward's, citing sales figures.

GM is ridding itself of all three brands. The struggling, bankrupt auto maker is selling Saab Automobile AB to Sweden's Koenigsegg Automotive AB, a low-volume producer of luxury sports cars.

Meanwhile, GM is killing the Pontiac division and selling its Saturn non-manufacturing operations to Penske Automotive Group. (See story below.)

“It's an interesting decision to kill Pontiac, considering it makes up 8% of GM sales, compared with 6% for Cadillac and 5% for Buick,” Anderson says. “Why eliminate Pontiac over Buick?”

One reason might be customer loyalty. More than 58% of Buick owners return to a GM brand to buy a new vehicle, the highest percentage of all GM divisions.

Saab is a different matter. Its 2008 retail registrations were only 17,376 last year, less than 1% of GM total sales. In the last two years, Saab sales in the U.S. have dropped more dramatically than the industry as a whole.

Of GM brands, Saab has the lowest number of customers (34.8%) loyal to the corporation, Experian data indicates.

“Saab owners are least likely to return to a GM vehicle,” Anderson says. “Saab just wasn't bringing a lot to GM. Not now, not 18 months ago.”