1. A motor vehicle having: prime mover means; at least first and second groups of one or more wheels; and a driveline operable to connect the prime mover means to the first and second groups of one or more wheels such that the first group and not the second group of one or more wheels is driven by the prime mover means when the driveline is in a first mode of operation and the first and second groups are driven by the prime mover means when the driveline is in a second mode of operation, the driveline including an auxiliary portion comprising releasable torque transmitting means by means of which the driveline is operable to connect the second group of one or more wheels to the prime mover means when the driveline transitions from the first mode to the second mode, wherein when in the first mode the driveline is operable to transition to the second mode responsive to an output of a reactive evaluator and a predictive evaluator, the output of the reactive evaluator being responsive to a determination whether an amount of wheel slip has exceeded a first prescribed threshold, the output of the predictive evaluator being responsive to a determination whether one or more conditions in respect of one or more vehicle operating parameters are met when the amount of wheel slip is below the first prescribed threshold.