A method for the fuel consumption reduction and/or power increase of an internal combustion engine of a motor vehicle is disclosed. A crank angle of a crankshaft is detected at which out of a cylinder the exhaust gases of a cylinder can be representatively measured on a lambda probe. The exhaust gas flow is measured on the lambda probe. A signal of the lambda probe is scanned at the time of the detection of the crank angle. A value indicated the detected angle and/or the scanned signal is sent to a computer. The value is corrected with the help of an exhaust gas pressure or exhaust gas back pressure model stored in the computer. An effective combustion lambda of the cylinder is calculated based on the sent values and a global lambda value stored in the computer and used to the control of the internal combustion engine.