Generally, vehicular ad hoc networks (VANETs) carry information public in nature, which benefits most of the vehicular nodes involved. Therefore broadcasting data becomes an interesting option for disseminating data in VANETs. Broadcasting also offers advantages of flexibility and lack of a defined topology. However broadcasting in dense networks can cause collisions due to unnecessary packet retransmissions (broadcast storm problem). Delay-based vehicular broadcast mechanisms have been proven efficient in reducing redundant packet transmissions in dense networks. However, packet losses due to poor wireless medium quality and high mobility render delay-based mechanisms highly incapable of reducing number of packet retransmissions. In this paper, we present a Delay-based Opportunistic Network Coding protocol called 'DONC', which uses Network Coding opportunistically to improve dissemination of broadcast data in loss-prone VANETs and reduce packet retransmissions. We simulate DONC protocol in ns2 and compare it with a delay-based VANET broadcast mechanism. Results prove that DONC protocol outperforms other delay-based mechanisms, specially in the scenario of lossy VANETs.