Federal safety regulators they have opened an investigation into 450,000 Dodge Durango SUVs and have upgraded an investigation into 217,000 Chrysler cars.

The National Highway Traffic Safety Administration NHTSA) opened the Durango investigation after receiving four complaints that the upper ball joint in the front suspension could fail, causing the driver to lose control. In two complaints, the wheel separated; in the other two, the suspension collapsed.

ConsumerAffairs.com has also received several reports of problems with the front suspension.

NHTSA also said it had 81 complaints that the ball joints wore out prematurely. The investigation covers 1998 through 2003 Durangos.

The upgraded investigation involves problems with the interlock between the ignition and the transmission on 1999 Plymouth Breeze and Dodge Stratus cars and Chrysler Sebring convertibles.

NHTSA said it had found 113 complaints where the key could be removed from the ignition without the transmission being in park, or where the transmission could be shifted out of park with the ignition off, both of which led to the vehicles rolling unexpectedly. The complaints include reports of 28 accidents and five minor injures.