While sociologists make careers of studying the ways automobiles affect the standard of living, the vehicularization of the American consumer is spawning a new generation of retail concepts that are themselves profoundly altering the country's retail landscape. And in some cases, the more things change, the more they stay the same.

Of every retail dollar Americans spend, about 31 cents goes into the family fleet of cars, according to the U.S. Census Bureau.

Almost nine of every 10 people go to and from work in a car. In most parts of the United States, a "normal" lifestyle - that is, a standard of living close to the national median - requires personal access to a motorized vehicle.

In America in particular, but in every other developed and developing nation, people are what they drive. And more and more these days, they drive to shop.

Four wheels and somewhere to go Before World War II, automobiles were in relatively short supply. Communities developed around pedestrian-oriented, mixed-use town centers that offered highly diversified activities to serve a relatively small trade area.

Many Americans lived, worked, shopped and played in small-town settings. Even large urban centers developed around boroughs or districts with town center characteristics.

The dynamics of such communities tended to support general, not specialized, retail opportunities. People ate lunch at the local diner; men took their dates to the local movie theater.

But four wheels and somewhere to go marked a defining characteristic of postwar prosperity.

By the early 1950s, most Americans either owned a car or dreamed of owning one. And with mobility came the slow but inevitable decline of the town center as a naturally evolving community.

As development shifted away from a pedestrian orientation to meet the demands of a vehicular society, communities began to take on new characteristics. Today, they are more dispersed - a 25 percent building-to-land ratio is typical - with lower densities and an explosion of new retail concepts.

Retail activity also is more isolated as distances between stores grows. And in some respects, location is less important as consumers begin to measure distance in minutes, not miles.

The clock is ticking As consumers are willing to travel farther to shop, retailers draw from a larger area. Faced with a trade area of 300,000 people instead of 3,000, they naturally begin to specialize.

Retail activity is divided into two main types: convenience and destination.

Convenience retail - service stations, drugstores, fast-food restaurants, dry cleaners, banks, etc. - are essential "pit stops" that exist somewhere between home, place of work and other retail destinations. Transactions at these pit stops normally take 15 minutes or less. Successful convenience retailers require ample exposure to a high volume of customers and good vehicular access.

The evolution of convenience activities along with consumer demand for a more vehicle-friendly world have given way to some surprising recent changes: the "co-branding" of service stations with fast-food restaurants; the flight of drugstores from neighborhood centers to highly visible, freestanding boxes at major intersections; and the location of bank ATMs inside grocery stores.

Destination retail involves places where people typically spend an hour or more of their time. Since Americans spend much of their time at home or at work, various support activities have evolved rapidly around these areas. For example, in-home recreational and entertainment amenities have enjoyed tremendous growth, and office buildings have witnessed a plethora of convenience-type activities, from sundries shops to day care to dry cleaners.

Destination retail comes in a variety of sizes, primarily neighborhood, community and regional. A neighborhood center typically is anchored by a grocery store configured to serve a population base of 7,500 to 15,000 people. It is supported by such ancillary services as a drugstore, florist, dry cleaner, phototography store, etc.

At larger community shopping centers, grocery stores have increased their scope of services, swallowing up ancillary retailers. More recently, hypermarkets have evolved to serve trade markets of 30,000 to 75,000 people, combining such activities as a grocer and a discount department store under a single roof - sometimes a single box - and corralling smaller services by leasing bays to outside vendors.

Regional retail centers can be further divided into specialized categories: regional malls, power centers and specialty/entertainment centers. With a wider selection of merchandise and, in some cases, better prices, such regional destinations have captured demandaway from neighborhood and community concepts in the same way that shopping centers captured demand from earlier town centers.

Regional centers typically are configured to serve a base of 250,000 to 400,000 people, most of whom live no more than 20 minutes away - by car, of course. The new breed of specialty/ entertainment centers relies on a population base of up to 1 million people.

Regional malls tend to position themselves as fashion centers and thus rely on shopping as a leisure activity. Power centers focus more closely on their respective retail categories, with an emphasis on big-ticket items that often involve an isolated shopping event - once the home entertainment center is loaded into the trunk, the customer usually heads home. Many of the stronger category-killers are finding they do not even need co-tenants to attract customers and, consequently, are developing freestanding, high-visibility stores on busy roadways.

As the retail market in America matures, new concepts succeed at the expense of existing ones. For example, Circuit City might replace dozens of neighborhood "TV Towns" and "Stereo Havens." New, aggressive retailers enter the market just in time to say goodbye to older, poorly positioned retailers on the way out of town.

To enhance the strength of a regional shopping destination - indeed, to attract a new generation of customers - specialty/entertainment centers are beginning to offer customers a more rewarding experience and a return to that personal, pedestrian setting of yesterday.

These types of centers are reviving some of the best characteristics of another era: They are safe, convenient, and pedestrian in scale. They appeal to a wide variety of customers with diverse leisure activities: specialty shopping, dining and entertainment, all grouped into a modern, vehicular town square. Major anchors in such centers can range from bookstores to megaplex movie theaters to musical instrument superstores.

More to go for These emerging concepts point to rather obvious trends. Convenience retail will be developed wherever there is demand, high visibility, lots of traffic and easy vehicular access. Likewise, convenience goods and services will continue to grow around major destination locales.

Destination retail centers, on the other hand, will increase in size, with greater focus on providing selection and service as well as enhancing the shopping experience. They aim for high consumer awareness, with the goal of becoming "the place to go" when a purchase decision is being made.

Moreover, as specialty/entertainment centers continue to evolve, there may be a return to a modernized, vehicle-friendly version of the old town center. The "local diner" may be a Cali-fornia-style bistro where customers bring their own hot sauce, and the "local movie theater" may be a multiplex cinema with stadium seating.

Maybe people are what they drive. But in retail development, they are where they drive.