A control system for a vehicle, the vehicle including an engine, a variable transmission for varying the transmission ratio between an output member of the engine and a ground engaging drive apparatus, the control system including at least one control apparatus which is operative to provide inputs to a controller, the controller being responsive to inputs from the control apparatus when the control system is operating in a first operating mode, to provide output signals to vary the engine speed, and when the control system is operating in a second operating mode, to provide output signals to vary the transmission ratio without changing the engine speed, and a mode selector control whereby an operator may select the first or second operating mode.