We study predecessor-following platoons in which each vehicle-to-vehicle (V2V) communication is affected by a different probability of successful transmission. We model the overall platoon as a stochastic hybrid system, and analyse its stochastic L2 string stability via a small-gain approach. We provide an explicit string stability condition that illustrates the interplay between the channel success probabilities, transmission rate, and time headway constant. We illustrate our findings through numerical simulations.