A diagnostic tool for a vehicle, includes a signal translator communicating with the vehicle in at least one protocol, an input unit for inputting information, a processor controlling a software according to the input information and communication with the vehicle, the processor controlling a recording of diagnostic data of the vehicle through the signal translator, a memory storing a software including a database controlled by the processor, the memory storing baseline data of the vehicle and recorded diagnostic data in the database, the processor comparing the stored baseline data and recorded diagnostic data, and a display unit displaying information according to the comparison between the stored baseline data and recorded diagnostic data. The comparison can also be made on a separate computer storing the baseline data and receiving the recorded data from the diagnostic tool.