By introducing the new world harmonized driving cycle (WLTC) in September 2017, which is addressing a more realistic speed profile or traffic conditions, the gap between the certification and road test is expected to be reduced in half.Additionally the EU Commission plans to monitor vehicles more closely. From 2020, devices for recording fuel and energy consumption will become mandatory in all passenger cars and light commercial vehicles, reflecting the average real world CO₂ emissions.During the type approval the OEMs have to prove that these so called ‘On-board Fuel and/or Energy Consumption Monitoring Device’ (‘OBFCM device’) is not deviating more than +/-5% compared to the fuel consumption value calculated from the carbon mass balance.OBFCM means that by using already existing devices in the vehicle, like the ECU, the quantity of fuel and/or electric energy used is being determined and stored.This is obviously a challenging target considering a typically uncertainty of the carbon mass balance determination of +/-3% with reference to precise direct fuel flow measurement.