Types of gases cars emit

Hydrocarbons (HC) -- unburnt fuel
Carbon dioxide (CO2)
Carbon monoxide (CO)
Nitrogen oxides (NOx)
Particulate matter (PM)
Formaldehyde (HCHO)
Non-methane organic gases (NMOG)
Non-methane hydrocarbons (NMHC)
Water vapor (H2O)
And others
Plus oxygen and nitrogen naturally