Diesel Catalytic Converter: Petrol engines use a three-way catalytic converter, which reduces oxides of nitrogen (NOx) and oxidise hydrocarbons (HC) and carbon monoxide (CO).

Newer diesel engines use an oxidation-type catalytic converter to oxidise hydrocarbons and carbon monoxide using the oxygen present in diesel exhaust.
The post-oxidisation also serves to reduce the soluble organic fraction of particulates. The catalytic converter consists of a ceramic block with a honeycomb structure: the channels of this honeycomb possess a high-performance platinum washcoat.