Translate the following English sentence to French:
"What is the point of measures, binding or otherwise, to encourage motorists to keep their speed down, when car manufacturers not only produce cars that greatly exceed speed limits but even make this a selling point?"
Que valent les incitations, contraignantes ou pas, demandant aux usagers de limiter leur vitesse, alors que les constructeurs automobiles, non seulement fabriquent des véhicules qui dépassent largement les vitesses autorisées, mais en font un argument de vente ?