2011 Chevrolet Impala

The National Highway Traffic Safety Administration is investigating vehicles from General Motors (if we had a nickel for every time we've written that this year). This time around, 320,000 Chevrolet Impala sedans from model year 2008 (the above photo is a 2011 model) are the focus, thanks to a defect petition filed way back in November, which NHTSA has just now opted to take a closer look at. This isn't a formal investigation just yet, although it could evolve into one depending on the review of the petition.

Donald Friedman, from Xprts, LLC, filed the original complaint, which focuses on the passenger airbag's Occupant Classification System. If any of this sounds familiar, it's because Friedman and Xprts aren't the only safety-focused folks asking NHTSA to take a closer look at the last-generation Impala. Clarence Ditlow and the Center for Auto Safety have also called out the OCS on certain last-gen Impalas. In those cases, a bad algorithm in the system would prevent the airbag from deploying if a seat's occupant bounced out ahead the impact.

While Xprts' complaint doesn't get into OCS specifics, it does call out the "software logic and algorithm," according to The Detroit News. The focus of the investigation revolves around a crash involving an elderly Texas couple and their 2008 Impala. Both occupants weighed around 170 pounds, yet only the driver's-side airbag deployed. The passenger airbag, meanwhile, was kept from deploying by the OCS.

Despite this case, NHTSA "has not identified reports indicating the presence of an OCS related defect in the 2004-2014 Impala," it said in a statement. "However, and in an abundance of caution, an evaluation of a limited scope of GM models, which will include a request for potentially related data on the MY 2007 to 2009 Impala, will be conducted to further evaluate the petitioner's allegations."

GM spokesman Alan Adler has told The News that the embattled company "will cooperate with NHTSA on its request for information. While the agency has 'out of an abundance of caution' asked for information on certain models of Impalas in the original defect petition, it is important to note that the agency has not opened a formal investigation."

More on this as it develops.