Embodiments of the invention relate to a motor vehicle controller operable automatically to stop and subsequently to restart an engine of a vehicle according to a prescribed control methodology. The controller is operable automatically to adjust an engine stop delay parameter in dependence on the value of at least one vehicle endurance parameter. The engine stop delay parameter corresponds to a period for which the engine of the vehicle remains switched on when it is determined that a condition exists allowing the engine to be switched off during the course of a drive cycle. The value of the endurance parameter is responsive to stop/start operations being performed during the course of a drive cycle. The controller is operable to adjust the engine stop delay parameter to prevent the value of the endurance parameter exceeding a prescribed maximum endurance value before a prescribed time period elapses.