A magnetic field generated by at least one coil operatively associated with a first portion of a vehicle responsive to a first signal from a signal source causes an eddy current in at least one conductive element operatively associated with or at least a part of a second portion of the vehicle. In one aspect, a circuit operatively coupled to the at least one coil generates a second signal responsive to a self-impedance of the at least one coil, wherein the second signal is at least partially in-phase with the first signal. In another aspect, a magnetic sensor is responsive to an eddy current in the at least one conductive element. In yet another aspect, the at least one conductive element comprises a metal sheet, film or coating of paramagnetic or diamagnetic material that is relatively highly conductive.