(EN) A motor vehicle controller according to the invention comprises: means for receiving a signal indicative of a surface friction parameter, said surface friction parameter corresponding to a coefficient of friction between a road wheel and a driving surface; means for receiving a signal indicative of a position of an accelerator control with respect to an allowable range of positions; means for determining a critical powertrain torque limit value in dependence at least in part on the value of the surface friction parameter; and means for providing a traction warning indication to a driver in dependence on the value of the signal indicative of a position of the accelerator control and the critical powertrain torque limit value.