An improved monitoring system for use with motor vehicles having a plurality of sensors for measuring the performance of the vehicle and a memory for storing information specifying data derived from the sensors. The invention includes a wireless communication link for transmitting the information to a terminal that is proximate to the vehicle. The terminal communicates information processed by the terminal to the operator of the vehicle. The present invention can be implemented by installing a connector into the standard scanner port on the vehicle. The connector includes a wireless link that emulates a connection to a conventional vehicle scanner by generating control signals on the appropriate conductors on the scanner port.