The Insurance Institute for Highway Safety (IIHS), which conducts research for auto insurers, has announced its first rankings of the 10 safest cars that combine frontal impact, side impact and head restraint measures into one single rating, according to Automotive News. Overall the association tested 16 small, 24 mid-sized and three large cars that were submitted by automakers who were asked by the IIHS to choose models that they felt might test well. Many organizations, such as the National Highway Traffic Safety Administration (NHTSA), assign ratings for each single category. Vehicles earning a gold designation received good ratings in all three categories, with vehicles that earned silver designations testing good in the frontal and side impact categories and acceptable in head restraints.The cars with the top safety scores were:-- Large CarsGold: Ford Five Hundred and Mercury Montego twin (if equipped with side airbags)Silver: Audi A6-- Mid-sized carsGold: Saab 9-3 and Subaru LegacySilver: Audi A3 and A4, Chevrolet Malibu (if equipped with side airbags), and Volkswagen Jetta and Passat-- Small CarsGold: Honda Civic (four-door)The IIHS added that its gold and silver labels only apply within each vehicle class and that consumers should not assume, for instance, that a small vehicle earning a gold rating is safer than a large vehicle that did not get a similar distinction. It also said that they are urging automakers to engineer their vehicles so that they will test well in all categories and perform best in the case of a real accident.