<div class="htmlview paragraph">Operation of a methanol engine on partially dissociated methanol is an efficient tool to improve energy efficiency and exhaust gas composition. The key factor of the system is the dissociation catalyst, which should be highly active, break down methanol completely with only minor formation of by-products, and unaffected by air addition. Laboratory scale screening tests showed that a noble-metal catalyst is best suited for this purpose. Engine tests employing such a catalyst gave up to 10 % better energy consumption and very favorable exhaust emissions as compared to engines on pure methanol.</div>