When gasoline gets inside a car, it leaves a strong odor for a long period of time. To get the smell out, you can't rely on just soap and water. More extreme measures are needed.
Pour an ample amount of baking soda onto the gasoline stain. Leave the baking soda on it overnight.
Vacuum up the baking soda the next day.
Mix one cup of warm water and 1 tsp. of dish soap in a bowl.
Dip a cloth into the soapy water and scrub the area where the gasoline was.
Rinse the area with plain water. Lay several paper towels over it.
Put a heavy object over the paper towels so they fully absorb the liquid. Allow the water to dry.