A National Highway Traffic Safety Administration (NHTSA) investigation into Jeep vehicles with a high rate of fires after a rear impact accident, has been expanded to include three models of Jeep vehicles. Originally the investigation focused on 1993-2004 Jeep Grand Cherokees, but data collected shows that certain Jeep Cherokee and Jeep Liberty models of the same years, may also experience the same problems.

In an earlier letter to Fiat, CEO Sergio Marchionne referred to the Jeep Grand Cherokee as a modern day Pinto for soccer moms. The Pinto, which had the fuel tank located behind the rear axle, was also found to experience fires after rear impact accidents. According to the Center for Auto Safety, there have been 184 fatal fire crashes in model year 1993 to 2009 Jeep Grand Cherokee vehicles and that 269 people have died as a result.

The Center for Auto Safety has been petitioning for a recall of the vehicles and said recently in an open letter to the NHTSA that “in NHTSA’s history of defect investigations and recalls, there has never been one where 4-year-old children in child restraints have burned to death in fire crashes until now. The letter continues to detail two instances where Jeep Grand Cherokee vehicles were rear-ended and burst into flames, killing two children.

If the investigation leads to a recall, approximately 5.1 million vehicles could be involved. According to Bloomberg News, the recall could be one of the largest recalls in history and could be a significant expense for Chrysler and Fiat, who have depended on these models for profitable in recent years.