Abstract: The invention relates to the measurement of the fuel consumption of a combustion engine. It relates to an apparatus which comprises two flowmeters (24, 26) which give temperature-compensated signals because their elliptical rotors 28 have the same coefficient of expansion as their chambers. Temperature sensors 36 permit the flow rates to be corrected before they are subtracted, the operations being carried out by a microcomputer 34. Application to the measurement of the fuel consumption of automobile vehicles.