Starting from the observation of the results of offset crash tests against a deformable element, the authors suggest it is possible to determine frontal aggressivíty criteria taking into account the effect of the car mass and stiffness Some hypothesis are considered like the stopping time of the vehicle and the energy lost by the vehicle after a pre-determined forward mouvement. It seems these parameters can give a good qualitative idea of the vehicle aggressivities but these hypothesis are still to be conñrmed and developped by other test results analysis in order to determine a more quantitative approach. A condition to determine a quantitative criteria based on the deformable element is to avoid bottoming-out during the crash, In fact, it was observed that, in the tests used for this analysis, the barrier very often bottomed-out and this occured more easily and earlier with the heaviest vehicles. In consequence, it is also recommended to adapt the barrier characteristics before going further in the development of aggressivity parameters in offset deformable crash tests.