Abstract: Shunt results from drive line resonance of a vehicle's transmission superimposing cyclic oscillations onto the speed of the vehicle's engine. A feedback loop comprising at least one of a band pass filter having a high frequency cut-off characteristic greater than first order, a feedback loop in which the loop gain is a function of transmission ratio, and a non-linear transfer element arranged to have a gain whose magnitude increases with the magnitude of the input to the non-linear transfer element. Additionally shunt may also be controlled by a feed-forward controller based on an engine demand signal.