By adopting different detection technologies, vehicles in Vehicular Ad-hoc Networks (VANets) are able to collect various kinds of information, like road traffic and environmental information, then, to transmit them to interested entities. Data collection in VANets is considered as an interesting application which aims at providing a safer, more efficient and more comfortable driving. In a previous study  we have proposed a Robust Clustered Data Gathering Protocol (CDGP), by using a Dynamic Space Division Multiple Access (D-SDMA) technique with a retransmission mechanism. However, CDGP provides a low collection efficiency given the large number of unused slots, which are wasted in a vehicle-to-vehicle communication (V2V). In this paper, we propose a new data collection protocol, which improves the data collection efficiency by using an enhanced Dynamic SDMA technique. Through simulation results we show that our new protocol enhances data collection efficiency and provides a reliable data collection.