Drivers involved in fatal U.S. car crashes were more often "lost in thought" than distracted by mobile phones, police data show.

Ten percent of U.S. auto accidents that caused death involved at least one motorist who was distracted, Erie Insurance Group said yesterday in a statement on its analysis of national crash data. Daydreaming and being "lost in thought" was the distraction 62 percent of the time, compared with 12 percent for mobile-phone use, Erie said.

Auto insurers including State Farm Mutual Automobile Insurance Co. and Allstate Corp. have publicized the risks of distracted driving. Carriers have been urging motorists to focus on operating their vehicles as mobile phones and cars add features that can take driver's attention off the road.

"The results were disturbing," Doug Smith, senior vice president of personal lines at Erie, said in the statement. His company advises letting incoming calls go to voicemail and pulling over to send text messages.

The AAA Foundation for Traffic Safety advises drivers to stay focused on the dangers of the road by playing the "what if" game and asking themselves how they would react to unexpected events on the road. Motorists should also identify and overcome any diversions that are responsible for daydreaming, the group said on its website.

"Treat driving as a complicated task requiring your full attention," the foundation said. "Remember 20 complex decisions are needed for every mile you drive."

The U.S. Department of Transportation declared April as National Distracted Driving Awareness Month as part of its effort to help motorists focus on the road. Geico, the car-insurance unit owned by Warren Buffett's Berkshire Hathaway Inc., advises drivers to shun food as well as phones when on the road, and to limit the number of passengers inside the car.

Among the biggest distractions for drivers are rubbernecking, talking with other people in the car, eating and moving an object in the vehicle, such as a pet, according to Erie's statement.

Police judgment is used to compile the data and could understate the extent of distracted driving because of motorists' reluctance to tell an officer their attention was off the road, Smith said.

Erie, based in the Pennsylvania city of the same name, looked at 2010 and 2011 data from the National Highway Traffic Safety Administration's Fatality Analysis Reporting System. State Farm issued a study in November that found almost half of drivers between the age of 18 and 29 use the Internet behind the wheel.

Allstate, the largest publicly traded U.S. auto and home insurer, is running a campaign on Facebook Inc.'s social- networking site to get teenagers to stop texting while driving. (Bloomberg)