The paper presents a methodology for creating dynamic characteristics of fuel consumption and intensity of emission of toxic components of exhaust gas. The source of data is the result of modal analysis of fuel consumption and emission intensity obtained from experimental drive tests. Two certified tests have been used: European NEDC and American Ff P- 75. A general algorithm for obtaining dynamic characteristics in the form of approximated functions is formulated on the basis of measured data. Examples of characteristics obtained for a real car with spark ignition engine are presented. The results obtained from experimental measurements and numerical simulations are compared and discussed.