System and method for power limitation in a vehicle

Input signals (12.13) from the driver are fed to a control circuit for a road vehicle power plant. The control circuit also receives input signals (8.14) from an authentication circuit (2). The system may include a function circuit and is connected (11) to an internal combustion engine (4) and (9,16) an electrical machine (6) working in parallel. The torque generated by the internal combustion engine crankshaft (7) is measured and a signal (19) is generated.