The demand for electric power in vehicles has been steadily increasing during the last years. Limited by the belt transmission the conventional generator will no longer be able to cover this demand in the future. A crankshaft-starter-generator (CSG) is able to fulfil this demand for electric energy and, in addition, to enable new features like the 'start-stop-operation' or the recovery of the braking energy in order to reduce emissions. A machine based on the principle of reluctance is a cheap and robust electrical machine. In order to development a CSG based on this kind of machine, two different types of reluctance machines are considered. Both, a transverse flux reluctance machine and a switched reluctance machine are designed according to the outer dimensions and the performance. Due to the short axial length of the machines three dimensional finite element calculations are used within the design process. Therefore the flux distribution is known at each position of the rotor. Using the integrating Maxwell stress tensor method the torque can be predicted. This static investigation one obtains that a higher number of stator teeth increases the available starting torque but, nevertheless increases the inductance of the phases of the machine too. In addition the rectifier according to its topology and characteristics has to be mentioned to assess the efficiency of the considered type of machine. A dynamic simulation is necessary to depict the behaviour of the entire system. Input values to the simulation are the specific distribution of the flux and of the torque according to the rotor position and to the current density. Within the paper the capability of reluctance machines in order to come into operation as a crankshaft starter generator are assessed. The best choice according to motor and generator operation in compliance with the requirements will be presented.