The IEEE 802.11 Medium Access Control (MAC) protocol has inherent weakness of channel wastage while operating a Mobile Ad hoc Network (MANET). In this paper, we therefore propose several new mechanisms we collectively name as Exhaustive MAC, to alleviate this problem and thus improve performance of IEEE 802.11 in MANETs. The basic principle of our proposals is to ensure utilization of channel capacity that is otherwise wasted. In addition to the concept of extra frame transmission during the wasted reservation period, our main contributions in this paper include (i) idea of RTS Release (RTSR), (ii) channel rescue and reuse, (iii) moving the state of the channel forward through ahead-of-time decrement of back-off timer. In addition, our proposed mechanisms are free from compatibility problems with standard