We propose an inter-vehicle communication system and investigate its performance. Due to employing physical layer network coding (PLNC) with fixed gain amplify-and-forward (AF) scheme on relay, our system is more practical in terms of implementation complexity than the ones using variable gain. Analytic results are derived under the cascaded Nakagami-m fading channel model assumption covering cascaded Rayleigh, double Nakagami-m, Generalized-K and conventional cellular channel models as well. As we investigate performance of the system, first we derive exact cumulative density functions (CDF) of the end-to-end signal-to-noise-ratio. Using this CDF, we obtain the exact closed-form outage probability. Then we derive the exact closed-form symbol error rate (SER) expression for various modulation types. Finally, we verify the analytic results by comparing with computer simulations. Our results show that the outage probability and SER performance decrease when the cascading degrees of the channels increase. (C) 2016 Elsevier GmbH. All rights reserved.