The pollutant emission from automotive internal combustion (IC) engines is highly susceptible to engine operation states determined by vehicle velocity processes. The article presents results of comparative examinations of specific distance pollutant emission characteristics determined from various vehicle driving tests. The specific distance pollutant emission was determined using vehicle type-approval and special tests as well as tests developed at the Automotive Industry Institute (PIMOT), treated as realizations of the stochastic process of vehicle velocity. The research results confirmed high susceptibility of the IC engine pollutant emission to the engine operation states, which endorses the usefulness of treating the conditions of operation of automotive engines as stochastic processes.