To date, the agency is aware of 84 consumer complaints and 361 warranty claims related to the alleged defect in the subject vehicles.In total, 382 subject vehicles reportedly experienced one or more wheel stud fractures, resulting in 7 alleged wheel separation incidents.Most of the reported wheel stud fractures occurred on subject vehicles originally equipped with 17 inch diameter steel wheels (368 of 382) as did all 7 alleged wheel separation incidents.Of the 7 alleged wheel separation incidents, 5 reportedly involved a wheel becoming detached from the subject vehicle's rear axle.The subject vehicles are designed with a safety margin that requires validation of proper wheel joint function with one missing lug nut and all other lug nuts at the minimum torque specification.If multiple stud fractures occur at a wheel location, analysis of reports indicates that the operator may observe vehicle vibration. If the vibration is ignored and the vehicle continues to be driven the remaining studs may fracture, resulting in a wheel separation.By letter dated December 5, 2011, the manufacturer notified the agency that it will conduct a safety recall (identified by NHTSA Recall No.11V-574 and Ford Recall No. 11S23) on certain 2010 and 2011 model year Ford Fusion and Mercury Milan vehicles to address the potential for wheel separation.The recall vehicles were originally equipped with 17 inch diameter steel wheels and were built from April 1, 2009, through April 30, 2009, and from December 1, 2009, through November 13, 2010.Approximately 128,616 vehicles are potentially affected as well as approximately 2,940 service steel wheels distributed to authorized Ford dealers.Ford has identified two distinct root causes of wheel stud fracture in the recall vehicles.First, certain steel wheel centers may have been stamped improperly such that the mounting pad lacks the necessary concavity, which reduces the diameter of the outermost radial points of contact with the brake rotor.This reduc