The invention relates to a method of detecting vehicles that park in a parking space zone, wherein excluded zones are recognized and/or determined that are not suitable and/or provided for parking vehicles; a transponder (40) is arranged in or at a vehicle, the transponder automatically repeatedly transmits a recognition signal; the recognition signal is received by at most three radio devices; and the position of the transponder is determined by means of a control device with reference to the time of flight and/or to the time of flight differences of the recognition signal from the transponder to the radio devices and with reference to the positions of the excluded zones.