On-board gasoline distillation for reduced hydrocarbon emissions at start-up

A method of reducing hydrocarbon emissions in the exhaust gas discharged from an engine having coolant and fueled by a primary fuel, the method comprising the steps of:

• supplying a portion of said primary fuel to a vapor separator;
• distilling said primary fuel to generate a secondary fuel;
• supplying said secondary fuel to said engine as part of a first fuel/air mixture during an initial engine operation period;
• terminating the supply of said secondary fuel to said engine after said initial engine operation period;
• supplying said primary fuel to said engine through a supply fuel line from a primary fuel tank as part of a second fuel/air mixture after said initial engine start-up period;
• purging said primary fuel from said supply fuel line during a post engine operation period;
• and
• filling said supply fuel line with said secondary fuel during said post engine operation period before a next engine operation period, whereby said supply fuel line does not have to be filled when said engine is restarted.