This paper compares the mass, composition and reactivity towards ozone formation of gasoline and methanol vehicle emissions. Methods used to estimate ozone forming potential include published reactivity scales and the EPA-OZIPM model. Evaluation of the available vehicle emission measurement data does not indicate any ozone benefit for methanol. The data show a wide range in the reactivity of gasoline vehicle VOC emissions. Emissions from vehicles with advanced emission control systems and low mileage have the lowest reactivity. Methanol vehicles emit essentially the same amounts of VOC (on a carbon basis), NOx and CO as gasoline-powered vehicles, and their VOC reactivity fails within the range for gasoline vehicles. When methanol fuels are compared directly with gasoline in flexible fuel vehicles, their VOC emissions have the same or higher reactivity.