In sheer diversity, imports enjoy competitive edge

At least part of this country's fascination with imported cars stems from the appeal of buying something different, offbeat, and unlikely to be duplicated around the next bend in the road.

On the eve of the 1984-model year, with cars made by foreign manufacturers now approaching one-third of all new-cars sales in the United States, imports logically would be expected to have lost some of their exotic charisma. Instead, the widespread proliferation of new models among importers scrambling for a piece of the lucrative US market means that for sheer technical diversity, the action ticks with the imports.

Small wonder, when you consider there are 20 major importers listing 97 models in the US. And unlike the penchant US auto companies have for creating a ''new'' car by adding a bit of chrome and decals, the 97 choices are distinctive cars from the ground up.

There's been some attrition of late, however.

The demise of the DeLorean Motor Company orphaned the handful of Irish imports it managed to produce. Likewise, Italy's Fiat, still one of the largest auto companies in Europe, has pulled out of the US market, although an independent importer plans to continue to import the roadster models, the Spider and XR-9.

Among the other changes, Honda joins the small but growing list of importers that have set up manufacturing plants in the US. Thus, if you buy a 4-door Honda Accord east of the Mississippi, it likely has been built in Ohio. Likewise, Japan's Nissan recently began producing pickup trucks in a plant in Tennessee, joining Volkswagen, which has been assembling Rabbits in Pennsylvania for the past six years.

Relatively new in the US are independent dealer networks that sell Japanese-built Isuzu and Mitsubishi cars.

These Japanese companies formerly were associated with General Motors and Chrysler, respectively, but are now trying to go it alone in the marketplace while still maintaining some links with the American auto firms. Both companies have been hindered by Japan's voluntary agreement to restrict the volume of US-bound exports. Late in the market, they are allowed to sell few cars.

Invisible to a customer in the showroom, the limits on importation of Japanese cars was negotiated in the midst of a recession that now appears to be nearly over. Even with the restraints, Japan today supplies some 80 percent of all imported cars sold in the US.

One side effect has been to provide an incentive to the Japanese to pour yet more money into product development, efforts that are strongly evident in the 1984 product lineup.

While Japanese engineers have devoted considerable money and talent to automotive development - and today have earned a well-respected niche in performance and road holding - their primary appeal is their low price.

The majority of Japanese cars sold in the US last year were priced under $7, 000, the bottom end of the scale for most domestic manufacturers. That's a situation the Japanese would like to change, since there are more profits in expensive cars.

Nissan typifies this trend with its new 300-ZX, replacement for the highly successful 280-ZX sports car, to be followed later in the year by an updated 200 -SX model.

Toyota, on the other hand, is redesigning its basic Corolla series, its bread-and-butter car. Toyota also demonstrates how quickly Japanese auto companies can sense a market trend by putting a hybrid van-wagon on the market. This joins another minivan from Mitsubishi to form a new class of vehicle - something larger and higher than a standard station wagon, but considerably more carlike than a passenger van.

Honda joins the upscale trend for 1984 by introducing a new fiber-glass-bodied sports car, first ever from Japan. It also fills in the low end of its market with a redesigned model of the Civic, which in recent years has been less popular for Honda than its higher-priced Accord.

Subaru and Mitsubishi also add performance to their lineup with new turbocharged engines for Subaru and the Mitsubishi Starion sport coupe.

Reviewing the new entries from Japan reveals a clear pattern of manufacturers attempting to move up from their former strength - basic transportation at a low cost.

Regardless, even the ubiquitous Japanese have been reluctant to challenge the American stronghold of intermediate and full-size cars. Instead, they have been adding performance as they seek new niches in the marketplace.

That's a strategy that has also been the salvation of old-line European manufacturers, which must compete in the US without the manufacturing-cost advantage of the Japanese.

As a result, European imports these days tend to represent extremes of price and performance, often at the same time. Exceptions are BMW, which has redesigned its smallest car, the 318i, and Mercedes, which also is introducing its version of the ''economy'' car, albeit in the Mercedes tradition, since its base price is about $23,000.

Offsetting its re-entry into what it perceives as its economy market, Mercedes also will be using larger gasoline engines in its big sedans, a break with past years when it relied on diesel power plants to improve fuel economy.

Volvo, likewise, will be introducing a new turbocharged engine to enhance performance, yet more evidence the automobile manufacturers no longer take the energy crisis very seriously.

The emphasis among most imports in 1984, in fact, is strongly reminiscent of the days when they were a scarce luxury rather than the huge slice of the market they represent today.

Style and performance still add up to something different.