Two of the types of particulate trap systems that have evolved to control exhaust particulate matter include the catalyzed trap system and the additive-regenerated trap system. Exhaust emissions from these two types of trap systems have been characterized and quantified as completely as possible. The two vehicles evaluated in the study included a 1986 Mercedes-Benz 300 SDL, which utilizes a catalyzed trap system, and a prototype Volkswagen, which utilizes an additive trap system. The vehicles were tested using a chassis dynamometer, a dilution tunnel, and a constant volume sampler. The exhaust emissions were evaluated as to driving cycle, presence of particulate trap, engine condition, trap condition, and fuel aromatic content. Emissions evaluated included the regulated exhaust emissions (total hydrocarbons, carbon monoxide, oxides of nitrogen, and particulates) and a number of unregulated exhaust emissions, including aldehydes and ketones, sulfate, metals and other trace elements, volatile organics, semivolatile organics, and 1,3-butadiene. Additional evaluations included the determination of the soluble organic fraction of the particulates and fuel economy by the carbon balance method.