Note on the compatibility of Carrera Wireless 2.0 with the previous 2.5 GHz Wireless+ system:
Wireless 2.0 handheld controllers can only be used with the Wireless 2.0 receiver; accordingly, the previous Wireless+ handheld controllers only work with Wireless+ receivers. However, parallel operation is possible if both a Wireless 2.0 receiver (20010122) and a Wireless+ receiver (20010112) Carrera are connected to the Digital Control Unit; you just need to ensure that the vehicle addresses are not assigned twice.
