Sprinkle the affected area with baking soda or cornstarch and let it sit for 30 minutes. The baking soda or cornstarch will absorb some of the gas. Brush it off into a plastic trash bag and dispose of it outdoors with your regular trash.
Apply a laundry pretreatment product to the gasoline area. Alternatively, apply a little bit of liquid heavy-duty laundry detergent. You can also mix powdered laundry detergent with just enough water to make a liquid and apply it to the affected area.
Rub the pretreatment product or laundry detergent into the affected area. Wait 5 to 10 minutes before laundering.
Launder the coat, per manufacturer directions. Use hot water if it is listed as safe for the fabric on the care label.
Smell the coat after washing it. If it still smells like gasoline, repeat Steps 1 to 3. After the smell is gone, air dry the coat outside or in a well-ventilated space.