million jeep vehicles the government claims are defective and prone to fires in rear end collisions. let's get more now from cnn's athena jones. >> reporter: in a rare act of defiance, car company giant chrysler refuses to recall almost 2.7 million vehicles as requested by the national highway traffic safety administration. for nearly two decades, some jeep suv models have had a tendency to burst into flames after a rear end collision. they are requesting that upgrades to the older models be installed to keep fires from starting. >> the definition of a safety defect is if it's a bad design, if it's harmful to people, and if it occurs repeatedly. and that's all been the fact here. >> reporter: the models in question are 1993 to 2004 jeep grand cherokees and 2002 to 2007 jeep liberties. the company says it's been working with the government on the fuel tank fire issue since