Many GERPISAs members intellectually admit the new paradigm, but very few implement it in their researches Three reasons 1.the auto-makers continue to speak about just in time, teamwork, costs reduction, etc 2.passing from a reasoning by tendencies to a reasoning by differences is not simple 3.the debate within GERPISA about the origin and limits of diversity Freyssenet M., The Origins and the Limits of the Productive Models Diversity.