General Motors announced that it will recall 181,516 MY 2006-2008 Chevrolet HHR vehicles not equipped with optional roof rail air bags for failing to comply with the requirements of Federal Motor Vehicle Safety Standard No. 201, 'Occupant Protection in Interior Impact.'What this means is that during tests, one of the upper interior occupant protection test points exceeded the standard's requirement. This standard specifies performance requirements to provide head impact protection for occupants. Chevrolet will deal with this problem by installing an energy-absorbing plastic piece to the headliner trim. The recall is expected to begin during March 2008.