A vehicle comprising: a motor vehicle driveline having: at least first and second groups of one or more wheels (12, 13, 14, 15); and control means, the driveline being operable by means of the control means to connect a torque transmission path from prime mover means to the first and second groups of one or more wheels such that the first group of one or more wheels (12, 13) and not the second group (14, 15) is coupled to the torque transmission path when the driveline is in a first mode of operation and both the first and second groups of one or more wheels (12, 13, 14, 15) are coupled to the torque transmission path when the driveline is in a second mode of operation, the driveline being operable to connect the second group (14, 15) to the torque transmission path by means of an auxiliary portion thereof, the auxiliary portion comprising first and second releasable torque transmitting means (22, 27) and a prop shaft, the first releasable torque transmitting means being operable to connect a first end of the prop shaft to the torque transmission path from the prime mover means, the second releasable torque transmitting means being operable to connect a second end of the prop shaft to the second group (14, 15) of one or more wheels, when the driveline is in the first mode the control means being configured to cause the driveline to transition to the second mode when one or more trigger conditions in respect of one or more vehicle operating parameters is met, the one or more trigger conditions being determined at least in part in dependence on a speed value corresponding to vehicle speed wherein the control means is configured to control the vehicle to operate in a selected one of a plurality of driving modes in each of which one or more vehicle sub-systems are operated in a prescribed one of a plurality of respective configurations, wherein the set of one or more trigger conditions are determined at least in part in dependence on the selected driving mode. at least first and second groups of one or more wheels (12, 13, 14, 15); and control means, the driveline being operable by means of the control means to connect a torque transmission path from prime mover means to the first and second groups of one or more wheels such that the first group of one or more wheels (12, 13) and not the second group (14, 15) is coupled to the torque transmission path when the driveline is in a first mode of operation and both the first and second groups of one or more wheels (12, 13, 14, 15) are coupled to the torque transmission path when the driveline is in a second mode of operation, the driveline being operable to connect the second group (14, 15) to the torque transmission path by means of an auxiliary portion thereof, the auxiliary portion comprising first and second releasable torque transmitting means (22, 27) and a prop shaft, the first releasable torque transmitting means being operable to connect a first end of the prop shaft to the torque transmission path from the prime mover means, the second releasable torque transmitting means being operable to connect a second end of the prop shaft to the second group (14, 15) of one or more wheels, when the driveline is in the first mode the control means being configured to cause the driveline to transition to the second mode when one or more trigger conditions in respect of one or more vehicle operating parameters is met, the one or more trigger conditions being determined at least in part in dependence on a speed value corresponding to vehicle speed the driveline being operable by means of the control means to connect a torque transmission path from prime mover means to the first and second groups of one or more wheels such that the first group of one or more wheels (12, 13) and not the second group (14, 15) is coupled to the torque transmission path when the driveline is in a first mode of operation and both the first and second groups of one or more wheels (12, 13, 14, 15) are coupled to the torque transmission path when the driveline is in a second mode of operation, the driveline being operable to connect the second group (14, 15) to the torque transmission path by means of an auxiliary portion thereof, the auxiliary portion comprising first and second releasable torque transmitting means (22, 27) and a prop shaft, the first releasable torque transmitting means being operable to connect a first end of the prop shaft to the torque transmission path from the prime mover means, the second releasable torque transmitting means being operable to connect a second end of the prop shaft to the second group (14, 15) of one or more wheels, when the driveline is in the first mode the control means being configured to cause the driveline to transition to the second mode when one or more trigger conditions in respect of one or more vehicle operating parameters is met, the one or more trigger conditions being determined at least in part in dependence on a speed value corresponding to vehicle speed