The invention concerns a kinetic energy recovery system for use in a vehicle driveline. The system has a flywheel (24) serving to store energy. A continuously variable transmission (32) serves to transfer drive between the flywheel and a driveline of the vehicle at a steplessly variable CVT speed ratio. The continuously variable transmission has a variator (34) which has a rotary variator input (40) and a rotary variator output (42). The variator serves to transfer drive between its input and output at a continuously variable variator speed ratio. The continuously variable transmission further comprises a shunt gear arrangement (36) having a first rotary shunt input which is drivably coupled to the rotary variator input, a second rotary shunt input which is drivably coupled to the rotary variator output, and a shunt rotary output which is drivably coupled to the flywheel.