The NHTSA began the investigation in August 2011 and has brought it one step closer to a recall by upgrading it to an engineering analysis.
The probe covers about 122,000 BMWs from the model years 2002-2008. The vehicles have electronic transmission and push-button start controls. There were some instances when the drivers thought their cars were in park when they were actually in neutral. The agency said the cars may roll away unexpectedly and cause a collision.
Investigators and BMW received 50 complaints regarding the issue.