s driving mode and a mud and ruts mr driving mode in some embodiments the selector also allows an u2018 automatic response mode u2019 to be selected in which the vehicle 10 determines automatically the optimum driving mode at any given moment in time the vehicle 10 has a vehicle control unit vcu 15 that is operable to implement a vehicle speed control function the vcu 15 may be described as implementing a speed control system the speed control function is controlled by a user by means of input controls mounted to a steering wheel 171 of the vehicle 10 the steering wheel 171 is shown in more detail in fig2 the input controls include a u2018 set speed u2019 control 173 actuation of which sets the value of a parameter driver_set_speed to be substantially equal to the current vehicle speed depression of a u2018 u2019 button 174 allows the set speed to be increased whilst depression of a u2018 u2212 u2019 button 175 allows the set speed to be decreased in some embodiments if the speed control function is not active when the u2018 u2019 button 174 is depressed the speed control function is activated the wheel 171 also has a pair of following distance control buttons 178 179 for setting a value of a parameter distance_following being the distance the driver desires the vehicle 100 to maintain behind a lead vehicle similar the vcu 15 is operable to control the vehicle 10 to maintain a distance behind a lead vehicle that is substantially equal to distance_following a first of the buttons 178 is operable to increase the value of the parameter distance_following whilst a second of the buttons 179 is operable to decrease the value of the parameter distance_following the vehicle 10.