How small is small? Here comes the minicar

Will US car buyers readily give up the relative performance and comfort of a compact for the noise and bounce of a minicar? Harvey Lamm, president of Subaru of America, has been talking about a Japanese-built minicar by the mid-1980s, while General Motors already has a deal with Suzuki to import up to 90,000 small-small cars by that time in order to test the market for such a vehicle. Other carmakers are debating the matter.

''We're going flat out on it,'' GM chairman Roger Smith told Automotive News, the trade weekly.

Also testing the demand, Purdue University's automotive transportation center has launched a three-year study to identify more efficient ways to make use of the private car in the United States. The micro-mini, or urban commuter car, could emerge as a major option to US families in which one member at a time is usually inside the car.

Dr. Tom Sparrow, director of the project, asserts that some 80 percent of all passenger-car trips include only one person inside the car. Thus, in a two-car family, a minicar, plus a car to hold the entire family, may make more sense economically than owning two midsize cars.

The Purdue project will also probe the option of shared ownership in other types of vehicles, in which a family would have the chance to use the vehicles on a specific number of days a month. The shared fleet could also be handled as a rental fleet, in which families would pay for the specific use they made of the optional cars.

The rest of the time the family would have its own minicar for the driver and perhaps one or two other passengers. Remember, however, the passengers - especially more than one - would have a tight fit.

Purdue families will rent the test cars at low cost.

Among the test fleet are a Suzuki Alto and the Daihatsu Cuore. GM will import an upgraded version of the Alto as part of its minicar program in the mid-1980s.

The midget car - 550-cc engines - has long been a popular option in Japan, mainly because of lower taxes as well as the lower cost to run and maintain the vehicle itself.

In a reverse action to that found in the US, Nissan has launched an attack on the so-called supermini by introducing its one-liter March in Japan, a car that is 10 inches longer than the Honda City supermini. Japan's No. 2 carmaker hopes to pull motorists away from the super-small job into a car with more room and performance, even if at higher cost.

Even the Japanese can't agree on how small is small.