NHTSA launching investigation into 2006-2008 Hyundai Sonata rust

The Detroit News reports the National Highway Traffic Safety Administration is investigating almost 400,000 Hyundai Sonata models over rust complaints. So far, NHTSA has received six complaints that Sonata models, built between 2006 and 2008, have allegedly suffered rear control arm failures due to subframe rust. Three of those occurred at highway speeds, and two resulted in the actuation of the vehicle's stability control system, though no one was injured. An investigation is typically the first step toward determining whether or not a safety recall is necessary.
This isn't the first recall for the Sonata.

Autoblog , NHTSA launching investigation into 2006-2008 Hyundai Sonata rust, NHTSA launching investigation into 2006-2008 Hyundai Sonata rust