Average exhaust emissions measured on vehicles fueled with fuel with additives were lower than those recorded on vehicles fueled with fuels without additives.
Cars fueled with detergent fuels had lower carbon monoxide (CO) and nitrogen oxides (NOx) emissions, respectively, by 22% and 20%, while unburned hydrocarbons remained largely unchanged. This positive effect can be attributed to the cleanliness of the intake system in combination with the control of deposits in the combustion chamber.
Exhaust emissions were also measured during this program. The results show that the spent catalysts on the two vehicle models, powered by detergent fuels, maintained their effectiveness over the 80,000 km road test program. However, this does not apply to machines running on base fuels. One of the base-fuel vehicles required a catalyst replacement after about 40,000 kilometers. At the end of this test, the quality of the spent catalyst also deteriorated significantly and showed signs of damage indicating overheating or melting of the catalyst bed surface.