In this work, the effect of using a Whale filter on the overall vehicle exhaust emissions was evaluated. A Whale filter is a South African patented diesel particulate filter designed to operate as a secondary diesel filter for the removal of particulate contaminants up to 0.5 microns in size in the fuel prior to injection. It is believed that removal of contaminants prior to injection may improve the fuel injection efficiency, thereby promoting efficient combustion, and thus resulting in reduced emissions and fuel consumption. Emissions tests were conducted on four different vehicle categories to validate this. All vehicles underwent pre-emissions testing prior to installation of the Whale filter. Each test was conducted for a period of approximately 20 minutes by varying the engine speed. The Applus + Autologic Vehicle Emissions Analyser was used to measure the emissions at each stage, and a similar procedure was followed to measure the emissions after installation of the Whale filter. The results showed a significant average reduction in carbon monoxide CO (35.3%), nitrogen oxides NOx (26.1%) and hydrocarbons HC (34.3%) emissions after the Whale filter was installed in the four vehicles.