The US road safety body has sparked the recall of all 11,300 Porsche Panameras after it highlighted a potential seatbelt tensioner problem.
The NHTSA said that "if the [Panamera's] front seats are adjusted towards an extreme position... it is possible that the function of the locking mechanism of the seatbelt mount can no longer be guaranteed."
It went on to suggest that the belts "may not provide adequate protection for the seat occupant, which may increase the risk of injury or death".
Porsche has immediately recalled all Panameras built and sold worldwide since last September.
The 400-plus Panamera owners in the UK can get an extra locking element fitted to the seatbelts of their cars at any Porsche dealership.