The NHTSA based its ruling after a year-long investigation on SAFE Research’s contention that a minor design change found its way into Explorers built during that time frame. Ford denies the contention, stating the redesign was for prototypes which never went into production. The automaker also points to other independent tests that showed its compliance with 216. SAFE Research expressed dissatisfaction with the NHTSA’s ruling. "I am extremely disappointed in the denial of our petition,” stated SAFE Research engineer Steven Forrest. “However, I am not the least bit surprised due to the obvious political and economic ramifications for Ford.”