Consumers are being urged to be concerned about Fords' safety priorities after the Mustang became the first car of any mainstream brand since 2008 to receive a two star crash rating.
Safety testing agency Euro NCAP said Ford hadn’t expected the European car to be crash tested and had missed off safety equipment available in the US.
Euro NCAP’s secretary general Michiel van Ratingen said: “Ford did not expect Euro NCAP to test the Mustang and chose not to fit safety technology in Europe which is available to its American consumers, and available on several other sports cars for that matter.
"Such an attitude to safety should trouble Ford’s customers, whether they are buying a high-powered muscle car or a regular family car.”
The results reveal the Mustang is designed to score well in the less wide-ranging US consumer tests.
The European variant has seen only those minor updates required to meet European (pedestrian) safety regulations and the forward collision warning system was removed when it was introduced here.
In the frontal offset test, the airbags of both the driver and passenger inflated insufficiently to properly restrain the occupants.
In the full-width frontal test, a lack of rear seatbelt pre-tensioners and load-limiters meant that the rear passenger slid under the seatbelt, implying higher risk at abdominal injuries in real life accidents.
In the side impact crash, the head of the 10-year dummy contacted the interior trim bottoming out the curtain airbag.
Ford says a face-lifted Mustang will be available later this year with pre-collision assist and lane keep assist as standard.
Euro NCAP said it expects to test the safety of this updated model when it is available on the European market.
Van Ratingen said: “We welcome any improvement, of course, and look forward to publishing a new rating for the updated model.
"However, more fundamental updates may be needed if the Mustang is to get a significantly better result. We therefore hope Ford takes the opportunity to invest in the changes needed now for future Mustang generations.”
In contrast, the Volvo S90 and V90 received five star Euro NCAP ratings today as a result of their "class leading safety".
"Both cars follow the trend set with the XC90, with excellent occupant protection, and a full suite of AEB functionality that includes pedestrian and cyclist crash prevention technology as well as its unique AEB system that is capable of identifying large animals," Euro NCAP said.
Video: Ford Mustang crash test