If you take just one small drink, one glass of wine or one bottle of mild beer, you may be a slightly safer driver afterward.

Any more alcohol than that and you rapidly become a dangerous driver, no question about it.

No one knows for sure why the small amount of alcohol tends to have the slight protective effect, but Robert Borkenstein of Indiana University, author of the study, suggests two theories: first, just a touch of alcohol may relax a driver enough to prevent over-reaction to traffic dangers, and second, awareness of having had a drink may make a driver more cautious.

Borkenstein's study was reported yesterday by the Distilled Spirits Council of the United States in a summary of some research it has financed.

Borkenstein, whose work also was financed by the old Department of Health, Education and Welfare, strongly emphasized the word "may" in concluding that a little alcohol may improve driving.

He did the original work in the 1960s, but it has been confirmed since, he said, in other studies. His research team first studied drivers' drinking habits by stopping, interviewing and breath-testing nearly 8,000 drivers at 2,000 accident-prone locations in Grand Rapids, Mich., which he says has the nation's best traffic-records system.

Researchers then went to accidents and hospitals to take breath tests on more than 7,000 drivers, both drinkers and nondrinkers, just after crashes.

They found the accident rate among very light drinkers was "about 10 percent" lower than that among abstainers.

"Very light," Borkenstein said, means about a half ounce of alcohol for a 150-pound person, less if you weigh less, a bit more if you weigh more. That translates to about one 1 1/2-ounce drink of 80 proof alcohol or a modest glass of wine or a beer, he said.

"For practical purposes," he added, "your chances of improving your safety record may be trivial or nonexistent. We report only averages, and different people react differently. We certainly don't advocate drinking before driving."

Neither does the Distilled Spirits Council, which says the "surest policy is 'Don't drink before driving.'"