The Insurance Institute of Highway Safety (IIHS) has revealed its Top Safety Picks for 2011, and 66 vehicles have earned the honor.

This year's tests featured a new variable that focused on roof strength, as the increasing number of rollover crashes have made the consideration more important in determining overall safety.

"We added the roof-strength requirement after our research confirmed the importance of roof strength when it comes to the seriousness of injuries to persons involved in rollover crashes," said Russ Rader, IIHS vice president of communications. "Federal studies on fatality and injury data showed that vehicles with stronger roofs resulted in the occupants having a much lower rate of serious injuries."

The big winners were Hyundai/Kia and Volkswagen/Audi, each of which walked away with nine total vehicles designated as a top pick. Subaru also earned some bragging rights, as every model it entered was named as a top pick.

Some of the individual models chosen by the IIHS included the Audi A4, Hyundai Sonata, Ford Explorer and the Toyota Sienna, which was the only minivan selected.

Drivers considering purchasing a used car can check out some of the Top Safety Picks from years past in order to ensure that their car of choice will protect them in an accident.