A combustion engine for a vehicle has an intake duct through which a fuel gas/air/exhaust gas mixture can be fed to a combustion unit of the combustion engine, and an exhaust gas recirculation system feeding in an exhaust gas from the combustion unit at an exhaust gas admission region to the gas fed to the combustion unit. A measuring device that determines the fuel gas/air/exhaust gas mass flow and the fuel gas/air/exhaust gas temperature is arranged in the intake duct upstream of the combustion unit and downstream of the exhaust gas admission region. A temperature sensor is arranged both in the exhaust gas recirculation system and in the intake duct, in each case upstream of the exhaust gas admission region, in addition to the measuring device, to determine a recirculated exhaust gas mass flow and/or an air mass flow fed to the combustion unit.