The larger a bandwidth, the greater ability a car stereo has of picking up all FM stations in a particular area.
If a user comes across two stations on the same frequency, the remedy is to change the Mhz rating of the FM Band Expander so it adjusts the stations accordingly.
An example of two stations appearing on the same frequency is illustrated In Wellington, New Zealand, where there are radio stations 90FM and 100FM.
If fitting an FM Band Expander into a vehicle in this region, a 10Mhz would not prove useful as it would put both radio stations on 80Mhz. However, a 12Mhz FM Band Expander would shift 90FM to 78Mhz and 100FM to 76Mhz, giving clear reception for both stations.