The major gas that comes out of cars (internal combustion engines) is carbon dioxide. There are many other gases as well, such as carbon monoxide, nitrous oxides, water vapor, and unburned gasoline.
I know it used to be roughly 15% Carbon Monoxide (CO) but now a vehicle's catalytic converter eliminates a good portion of that, another gas would have to include a portion of unburnt fuel, seeing as...
Complete combustion from a car results in CO2 (carbon dioxide) and H2O (water) as the byproducts. However, car engines are not perfect converters of fuel into CO2 and H2O. The engine's incomplete...