Hydrogen is unique among alternative fuels in its ability to burn with large amounts of excess air (ultra lean burn) with no carbon-related combustion products. Hydrogen also has a unique ability to burn on the surface of a catalyst, starting from room temperature. Hydrogen may be used in highly “leveraged” ways with other alternative fuels by taking advantage of these unique properties during the crucial period just after the vehicle is started from a cold condition. A methanol vehicle was started on pure hydrogen and idled at ultra lean conditions (oxygen rich exhaust) while injecting hydrogen at the inlet to the exhaust catalyst. Over 15 kW of chemical heating power brought the catalyst to light-off temperature quickly. “Cold 505” transient emissions tests show reductions in all pollutants which far exceed the fraction of the fuel energy supplied as hydrogen.