Wireless communication protocols based on vehicular ad hoc networks (VANETs) have potential applications for improving on-road experiences including road safety. This work investigates relay cardinality impact on the performance of sender-driven multi-hop messaging protocols over VANETs. The aim of this study is to identify suitable relay set cardinalities for varying spectrum of applications, with emphasis on active alert messaging protocols. Impact of relay cardinality is evaluated while considering end-to-end communication delays and reachability of messages as performance measurement metrics. Performance evaluation is conducted for broadcast messages over large coverage and densely populated networks. Simulation experiments reveal that reachability of the sender-driven broadcasts improve to a certain extend with increase in relay cardinality, but at the expense of increasing end-to-end delays.