Carbon dioxide (CO2) is one of the basic greenhouse gases and according to some opinions their influence upon warming the earth climate is significant. Acceptance of this prognosis has lead to worldwide legislative limitation covering all CO2 emitting engines.The paper reviews the relationship between CO2 emissions and fuel consumption in a range of automobiles (with SI and CI engines) presented for type approval over last four years (1996-1999). The paper presents an analysis of the results of an examination of the CO2 emission and the fuel consumption of more like 150 automotive vehicles (M1 and N1 categories), European, Japanese/Korean manufacturer and the US. The procedures used in the examination for approval in the presented scope have been described and several results of these examinations conducted in Poland in accordance with the requirements of the Regulations No. 101 ECE UNO (directive 93/116 EC) have been evaluated.The evaluation of the possibilities of fulfilling the existing and future requirements of the above-mentioned emissions CO2 have been discussed. A study of some technical exercises in the reduction of fuel consumption was described as well.