The impact of mileage, from 4000 to 96 000 km, on the exhaust emissions of several nonregulated pollutants is studied in the case of several Euro 3 diesel passenger cars, tested on the New European Driving Cycle. The results show that the emissions of the four regulated pollutants remain within the regulatory limits. Exhaust NO, and particulate matter remain constant with mileage, while the emissions of hydrocarbons and CO increase, because of a partial deactivation of the oxidation catalyst. Exhaust emissions of many nonregulated pollutants are not particularly affected by the partial deactivation of the catalyst. Exhaust concentrations of methane, 1,3-butadiene, benzene, the main carbonyl compounds, and particulate sulfates remain constant. However, the exhaust concentrations of some other nonregulated pollutants, such as exhaust olefins, heavy HCs, heavy carbonyl compounds, and light polycyclic aromatic hydrocarbons (PAHs) increase. The emissions of heavier PAHs and N2O decrease with mileage.