An apparatus for optimizing operating characteristics of an internal combustion engine on the basis of torque variations based on a test signal, wherein the maximum output torque is determined directly on the basis of the torque signal and the specific fuel consumption is determined indirectly from the torque signal via the efficiency. Either the maximum output torque or the minimum fuel consumption is optimized, depending on the engine load range. Additional apparatus is described for simultaneously optimizing the ignition angle on the basis of torque signals, wherein individual test signals are associated only with individual cylinders or groups of cylinders and the corresponding torque variations relating to the individual cylinders are ascertained and processed.