The measurement of fuel consumption and CO2 emissions has become mandatory during the type approval procedure for M1 vehicles (cars) in the EU with the introduction of directive 93/116/EC. Within the context of the discussions about the global warming of the atmosphere the lowering of the CO2 emissions and thus the lowering of the fuel consumption has become an important target for the vehicle industry. But the measurement method of the above mentioned directive is not suitable to consider influences of additional aggregates like air conditioning systems or the influence of  new transmissions (6-speed gearboxes, advanced automatic gearboxes) allowing fuel consumption reducing gearshift strategies. Without these influences the CO2 emissions of the car fleet cannot be calculated realistically enough.