Modular vehicle system having increased operational safety

The invention relates to a modular vehicle system with an electric vehicle (2) and a module (16) that can be connected to the electric vehicle (2) by means of a plug connection, wherein the electric vehicle (2) has at least a power on-board network (3) for supplying energy to an electric drive unit (6) of the electric vehicle (2), a control device (9) for communication with the module (16), and an interface (15) connected to the power on-board network (3) and the control device (9) for connection with the module (16), which interface (15) forms a first element of the plug connection, wherein the module (16) has at least an electrical assembly, a module control (23) for communication with the control device (9) of the electric vehicle (2), and a connection element (17) connected to the electrical assembly and the module control (23), which forms a second element of the plug connection, wherein the interface (15) of the electric vehicle (2) is detachably connectable with the connection element (17) of the module (16) in order to connect the electrical assembly of the module (16) with the power on-board network (3) of the electric vehicle (2), and wherein the interface (15) has a first NFC device (43) and the connection element (17) has a second NFC device (104), which are designed for near-field communication with each other in order to connect the control device (9) of the electric vehicle (2) with the module control (23). The invention further relates to an electric vehicle and a module for such a modular system as well as a method for connecting the same.