In order to examine the the motor vehicle's influence on the environment in its entirety, attempts have been made to draw up so-called eco-balance sheets. These balance sheets include vehicle production and disposal as well as vehicle operation.
As far as individual components are concerned, the powerplant has a significantly larger influence. In this respect, exhaust emissions are the focus of interest. The automobile makes a significant contribution to air pollution, as shown in the figure.
Through statutory measures, the permissible values of the certain pollutants have been reduced step by step.
The four significant toxic components of combustion engine exhaust are: carbon monoxide (CO), unburned hydrocarbons (HC), nitrogen oxides (NOX), and sulphur dioxide (SO2).
The Table on the right shows the proportion of toxic emissions related to vehicular traffic in the total emission of specific toxic substances in West-Germany in 1990.