This work aims to review the scientific knowledge on the effects of niobium in the steels used in the automotive sector, for car-body applications, by means of an extensive literature survey. Environmental issues lead to increasingly stringent regulation for CO2 emissions; therefore, weight reduction is required for passengers cars. First, the effects of niobium in steels are discussed. Niobium, used as a microalloying element, improves mechanical strenght, allowing a reduction in weight, but it can also enhance formability, energy absorption or fractures resistance. The strenghtening mechanisms through which it acts are mainly two: grain refinement and precipitation. The first, in particular, has the greatest advantages, since it improves both strenght and toughness at the same time.