Buckling up: it differs by area and type of car

If you drive a small car, are you more likely to ''buckle up'' before you leave the curb? The National Highway Traffic Safety Administration (NHTSA) says yes, claiming that belt-use rates in small cars are about twice those of large cars.

Researchers for the Insurance Institute for Highway Safety (IIHS) disagree, reporting in the May issue of The American Journal of Public Health that safety-belt usage may be tied instead to imports and the geographic location of the drivers, rather than car size.

In fact, in observing thousands of vehicles in all parts of the United States , the safety institute says that safety-belt usage for small domesticm subcompact cars ranges from 9 percent in New England to 16 percent in the West, with an average of 12 percent for the entire country.

Among small subcompactimportedmcars, however, the usage figure is highest in New England: 26 percent, vs. 24 percent in the West and only 17 percent in the Southwest. The average for the entire country is 22 percent. For domesticm small subcompacts, the average is 12 percent; and for importedm small subcompacts, 22 percent.

Among full-size domesticm cars, the figures run from 4 percent in New England to 10 percent in the Southeast to 15 percent in the West.

Belt-usage stretches from 6 percent in New England for domesticm compact cars to 8 percent in the North Central region; and from 10 percent in the Southwest to 16 percent in the West.

As for the importedm compact cars, the buckle-up rate runs from 23 percent in New England to 26 percent in the Southeast, 31 percent in the North Central region, and 32 percent in the West.

The NHTSA has theorized that the difference in belt-use rates was largely the result of a possible perception by motorists that small cars are less safe on the road than larger cars.

The IIHS researchers declare that data collected in the two years ended in November 1979 showed that ''there is no clear relationship between driver lap/shoulder belt use and car size per se.''

The report shows that New England motorists who drive a Detroit-built car are far less likely to ''buckle up'' than those who drive an imported car in the region.

The split in the West, by contrast, is far less dramatic.