Maximum exhaust emission levels for passenger vehicles in grams per kilometer (g/km)
In order to meet the increasingly stringent emission standards, exhaust gas after treatment will increase in significance even for diesel engines, despite the progress made with regard to engine modifications.
By constantly improving the injection systems (direct injection in conjunction with constantly increasing injection pressures) and their electronic control, the performance, economy and comfort of the diesel engine has steadily been increased.
Also of significance is the reduction of exhaust gas emissions, the maximum levels of which have to be continuously improved due to legal requirements.
The measures inside the engine (high injection pressures, nozzle design, timed introduction of fuel and combustion chamber shape) have lowered the CO, HC and diesel particulate emissions to a large extent.
The NOX emissions produced by excess air in diesel combustion are effectively reduced by exhaust gas recirculation systems which are constantly being improved.
The oxidation catalytic converter, in use for some years now, represents the first stage of exhaust gas after treatment. It further reduces HC and CO emissions.