Exhaust CO2 emitted from passenger cars is one of the major greenhouse effect gases. Several parameters influence the exhaust CO2 emissions of each passenger car: its characteristics (fuel used, vehicle weight, ...) and its use (annual mileage, driving conditions, ...). CO2 emissions from passenger cars decrease during last years; however, this decrease seems to reach its limits. Several parameters of the EU15 new PCs market, such as new passenger cars registrations, type of fuel used, engine capacity, max. power, max. specific power, segment distribution, vehicle weight and their CO2 emissions on the New European Driving Cycle are analyzed here. The target is to find the real market parameters influencing exhaust CO2 emissions. Because of the many data used and the parameters examined, this first part of the work is focused on the average values of each parameter studied and the values of each country, while the second part is based on the analysis of each PC segment and the third one on the analysis of the major brands presented in the European market. (c) 2010 Elsevier Ltd. All rights reserved.