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In this paper, we present the results of an experimental study on particulate emissions of gasoline vehicles. The objective of the project was to investigate the particulate emissions on the basis of number and total mass and to gain experience in the influence of the sampling method on the results. The measurements were carried out with three passenger cars at a chassis dynamometer. Two vehicles with premixed combustion and one direct injection engine were tested at constant loads and driving cycles. For the aerosol sampling we used a standard CVS system, an ejector and a rotating disk unit. The samples were analyzed by SMPS and ELPI. Samples for gravimetric analysis were taken downstream of the CVS tunnel and from a mini tunnel. The results show that all three vehicles produce significantly less particulate in number and mass than a common diesel vehicle.

Analysis of non-legislated engine-emission components, with different exhaust-gas after-treatment techniques, is an important air quality objective. This paper reports the results for various nitrogen oxides, ammonia and differentiated hydrocarbons emitted at part load from a small 4-S SI engine. It was operated with gasoline, with CNG and with two different three-way catalytic converters. CNG produces less HC and less aromatics. But the HC conversion rate is insufficient. This is due to the lower exhaust gas temperatures, at part load with CNG, and due to the higher stability of light HCs. CNG affects the λ-regulation window, of the investigated system, such that the NOx conversion rate is lowered. In the rich domain of the λ-regulation window, the NO & NOx emissions after catalyst were lowest, while the NH₃ formation was most intense, and vice versa.