Multiple channels have been allocated in the 5 GHz spectrum for vehicular communications worldwide, however, due to the limited allocated bandwidth, simultaneous communications occurring over nearby channels may be affected by adjacent channel interference (ACI). Due to ACI, packet reception may be unsuccessful and transmissions may be delayed. In this work, we investigate the ACI phenomena in multichannel vehicular networks to shed light on their effects, with focus on the transmitter-side. To this purpose, a simple analytical model is introduced along with a preliminary evaluation. Suggestions are also provided about the usage of adjacent channels so to minimize side effects on the communication quality. © 2014 IEEE