Abstract: A system for monitoring, recording and displaying vehicle operating parameters is described, which is capable of simultaneously providing operating data for the driver, an on board summary of critical trip parameters, and storage of monitored vehicle operating data for subsequently generating reports off-line which describe in detail the selected trip information. The system consists of a Vehicle Mounted Unit [VMU] which accepts inputs from a variety of sensors. Using these inputs, the VMU continuously computes the various parameters in order to provide the operating data as well as the on board trip summary. Detailed data are simultaneously stored in the VMU memory for subsequent processing by an off-line computer. The contents of the VMU memory may be transferred to the computer in a variety of ways.