Kirkwood - At some supermarkets around the country, shoppers can pick up a gallon of milk- and fill their gas tank with gallons of fuel at the same time.

And this year, a Shop 'n Save store here is poised to offer a similar gas-and-groceries mix.

The supermarket chain, which has 38 stores in the St. Louis area, is planning to open a fuel center at its store on Manchester Road in Kirkwood, adding to fuel pumps already installed recently at four of its other stores, in St. Ann, Alton, Wood River and Edwardsville.

"It's just adding value to our customers," said Rebecca Herbst, a spokeswoman for the chain. "It's one-stop shopping."

When supermarkets are competing for customers' dwindling dollars, it could also prove to be good business strategy, some analysts say.

"It's an added draw to the store," said independent supermarket analyst David J. Livingston. "It has to do with continuity, bringing the customer in. It's like another department."

The centers, and accompanying rewards programs, have proved popular at other chains.

"It becomes a traffic draw, and it gets people on the lot," said Jim Hertel, a supermarket analyst for Willard Bishop, a retail research group. "It can also convert unproductive space to revenue generation."

The groceries-and-gas model has been around for more than a decade, analysts say, and Shop 'n Save-a Kirkwood-based unit of Minneapolis-based Supervalu-has come late to the gas game. Other chains in the area have opted out of the gas business and say they have no plans to jump in.

Within the St. Louis area, shoppers can only gas up and buy a full range of supermarket food at a handful of Sam's Clubs, Wal-Marts and Costco stores, in addition to the aforementioned Shop 'n Saves. Schnucks and Dierbergs don't have fuel centers in the area, although Schnucks has eight at stores in Tennessee and Mississippi that it bought in 2002 from another chain.

Other grocery chains, including the massive Cincinnati-based Kroger, which has some 750 fuel centers at its supermarkets, entered the fuel business about a decade ago.

But last year, when gas prices climbed over $4 dollars a gallon, the gas business began to look especially appealing. High gas prices may not have meant more profit for supermarkets, but they gave the appearance of greater sales.

"When you see gas at $4 a gallon, that looks really good on your balance sheet," Livingston said. "Wall Street likes that. It's all psychology."

The Shop 'n Save fuel centers, which will be called Fuel Express, also offer rewards programs, in which shoppers who spend a certain amount on groceries can earn discounts on gas. Other chains, some of which also got into the gas business last year, are offering similar programs, though some don't have on-site gas stations.

One of those is the Virginia-based Ukrops chain, which launched a "fuel perks" program last summer.

"It came at a time when gas was soaring and relief was desperately needed," said Josh Bracey, a spokesman for the Ukrops chain. "Since then gas has dropped in half."

Still, Bracey said, the program is working. The store pays for the discount the customer earns at the gas station, but "that's OK because they're doing most of their shopping with us."

The Giant Eagle supermarket chain, with 221 stores in Ohio, Maryland, West Virginia and Pennsylvania, opened a separate chain of convenience stores that have gas stations attached. When shoppers spend money at the supermarkets they earn discounts at the gas stations, while picking up a snack at the same time.

"They certainly complement each other," said Dick Roberts, a spokesman for the chain. "It's all conceptualized to drive business to the big box."

Shop 'n Save says its plans in Kirkwood are under way, though it can't promise there won't be any snags in the zoning approval process. The chain is also opening a fuel center at one of its stores in Springfield, Ill.

ggustin@post-dispatch.com | 314-340-8195