Vehicular Adhoc NETworks (VANETs) are the key to the future of intelligent transportation systems. An efficient MAC protocol is of greater importance to meet the strict deadlines of safety related applications in VANETs. This work introduces a novel TDMA-based variable interval multichannel MAC protocol (TM-MAC) for VANETs. TM-MAC employs TDMA along with variable interval multichannel scheduling for providing a reliable and efficient broadcast service over a lossy wireless medium. TM-MAC reduces transmission collisions thus making Control CHannel (CCH) more reliable and provides high throughput over Service CHannel (SCH) via maximum channel utilization. The scheduling strategy ensures that vehicles are assigned a slot instantaneously. Moreover there is a reduction of almost 50 % in number of vehicles incurring merging collisions when compared with VeMAC (Omar et al. in IEEE Trans Mob Comput 12(9):1724–1736, 2013), an existing and recently proposed TDMA based MAC protocol. This reduction in merging collisions increased the packet delivery ratio by almost 25 % when compared with VeMAC. Extensive simulations which were done over a realistic city scenario connote the superiority of TM-MAC over existing schemes for a wide range of traffic conditions. © 2015, Springer Science+Business Media New York.