Although studies can be found in the literature that present emissions inventories associated with different types of automobiles, distinct technologies or various stages of their life cycles, they do not enable us to compare the environmental impact of the complete life cycle of two vehicles. This is because there is no valid emissions inventory for all types of automobiles that covers all the life cycle stages (the cradle to grave approach). This paper proposes a method to estimate the principal types of emissions throughout a vehicle's life cycle based on primary data (weight, year of manufacture, engine technology, fuel type used, etc.). The proposed method requires neither sophisticated life cycle assessment software nor knowledge of specific information on individual vehicles. The proposal has been validated by analyzing three different gasoline and diesel-fueled internal combustion engine vehicles and by considering a life span of 100,000 km. (C) 2015 Elsevier Ltd. All rights reserved.