Internal combustion engine, configured as a gas engine, for a motor vehicle, with an intercooler which is arranged in an air mass flow feed upstream of an apparatus for the addition of fuel, and with a measuring device for determining the air mass flow, the measuring device having a sensor system (19, 20) for measuring a pressure loss across the intercooler, the measuring device having, furthermore, a computing unit as evaluation unit, by way of which, in an intercooler model which is stored there and in which the intercooler forms a geometrically constant throttle for the air mass flow flowing through, can be calculated at least from the pressure loss which is measured by means of the sensor system (19, 20), the measuring device having a sensor system for measuring a pressure loss across a throttle valve and for measuring a throttle valve position, the throttle valve forming, in a throttle valve model which is stored in the computing unit, a geometrically variable throttle for the air mass flow flowing through, with the result that the air mass flow can be calculated by means of the computing unit at least from the respective pressure loss at the throttle valve and the throttle valve position, and the measuring device being configured in such a way that the determination of the air mass flow can be carried out in the low load range of the internal combustion engine by means of the throttle valve model, and in the high load range by means of the intercooler model, characterized in that, in at least a middle load range lying in between, the determination of the air mass flow takes place by means of the throttle valve model and the intercooler model, and a continuous comparison of the results of the two models can be carried out, possibly in conjunction with lambda closed-loop control. with a measuring device for determining the air mass flow, the measuring device having a sensor system (19, 20) for measuring a pressure loss across the intercooler, the measuring device having, furthermore, a computing unit as evaluation unit, by way of which, in an intercooler model which is stored there and in which the intercooler forms a geometrically constant throttle for the air mass flow flowing through, can be calculated at least from the pressure loss which is measured by means of the sensor system (19, 20), the measuring device having a sensor system for measuring a pressure loss across a throttle valve and for measuring a throttle valve position, the throttle valve forming, in a throttle valve model which is stored in the computing unit, a geometrically variable throttle for the air mass flow flowing through, with the result that the air mass flow can be calculated by means of the computing unit at least from the respective pressure loss at the throttle valve and the throttle valve position, and the measuring device being configured in such a way that the determination of the air mass flow can be carried out in the low load range of the internal combustion engine by means of the throttle valve model, and in the high load range by means of the intercooler model, characterized in that, in at least a middle load range lying in between, the determination of the air mass flow takes place by means of the throttle valve model and the intercooler model, and a continuous comparison of the results of the two models can be carried out, possibly in conjunction with lambda closed-loop control.