Since 1997 in Belgium, the market share of vehicles equipped with diesel engine has grown up from 50% to nearly 80%. Most of the drivers are using diesel cars for private or company purposes and gasoline powered engine vehicles sales dropped dramatically since then. This evolution is clearly a game-changer regarding the type of regulated emissions we can find as dominant. Tests and analysis for this work focused on diesel passenger cars and one of the main drivers for that was the great demand of new cars fitted with exhaust aftertreatment devices (DPF, DOC, LBC etc.).In this paper the performance of soot filters were measured and presented, based not on the NEDC but on the heavy duty 13-Mode test cycle which emphasize mainly at low-speed driving conditions, such as all passenger cars are running currently, and is also characterized by low average engine loads and low exhaust temperatures. Two modern test cars were used and tested under the same operational conditions on a chassis dynamometer. All tests were conducted at KdG University College in Antwerp. Exhaust gas emissions generated from both test cars were measured and analyzed and a comparison was made. The first car was a Peugeot 807 HDi FAP 2002 year of construction, fitted with a factory installed soot filter and the second one was a Volkswagen Golf TDI 2003 year of construction without particle trap. All regulated emissions were controlled as well as lambda values and oxygen content in the exhaust fumes. Analysis of the results showed that the Volkswagen car even though was not equipped with any particle trap was able to emit fewer particles than the Peugeot in some test points. During operational conditions and at the same engine torque results, it was found that having the particle trap equipped, at high loads, specifically, at points 10 and 12 of the 13-Mode test; the Peugeot had worse results than the VW Golf. This was linked to the increased fuel consumption originated by the increasing backpressure caused by the particle trap as well as exhaust after-treatment strategy. All the soot content measurements were made using an AVL 415 Smoke Meter, and using conventional diesel fuel, accordingly to the norm ISO 10054.