A portable data exchange device including a data input, a data output, and
a memory is incorporated into a mechanical or electronic key that is
required for operating a motor vehicle. The data exchange device can
exchange data bi-directionally or uni-directionally with a data
processing device in the vehicle and with an external input/output
terminal. The data may include vehicle-specific and/or driver-specific
data relating to various systems of the vehicle. The data are transmitted
to and from the device in the key in a wireless or direct-contacting
manner. This device incorporated in the key avoids the need for carrying
a separate data unit for exchanging data between the on-board data
processing device of the vehicle and the external input/output terminal.