The Farmers Group Inc. auto insurance company examined 2006 data provided by the Department of Transportation. Researchers determined that drivers who used seatbelts were 70 percent less likely to be killed than drivers who were not belted in.

Kevin Mabe, an economist for the company, said the study corrected for variables like traffic conditions at the time of crashes.

The study yielded other unsurprising findings. Head-on crashes are more likely to be fatal than rear-end ones, large vehicles like trucks and sport utility vehicles provide more protection than small ones, and fatalities are 10 percent more likely on wet roads than dry ones.

New drivers and older ones are more likely to be killed than the middle-aged. Crashes involving rollovers and fires are also more likely to be deadly.

"Nighttime and winter driving tended to produce more deadly accidents and drivers should continue to exercise additional caution," Mabe notes.