difference is divided by the target boost pressure value pldsoll the result is delivered together with the engine speed nmot sensed by rotation speed sensor 12 to a characteristics diagram kf 240 in which an indicator is determined by two dimensional characteristics diagram interpolation the variable determined in characteristics diagram 240 is converted into a normalized dimensionless variable typically in the value range between 0 and 1 this variable represents the dynamic indicator that is then in step 242 delivered in turn to the egr system or to the injection system controller the engine speed nmot is used here because the mass gas flow through the engine directly dependent on the engine speed represents an important variable for characterizing the maximum achievable dynamics for boost pressure buildup and different relative boost pressure deviations at different engine speeds nmot can thereby be handled differently the dynamic indicator can also be used for applying control for example to an electric motor e machine or an electrical auxiliary compressor e booster that is provided in order to accelerate the buildup of boost pressure and torque in this case the dynamic indicator is used so to speak as a u201c trigger u201d for applying control to.