A system for executing diagnosis of vehicle performance using satellite telemetry technology includes a diagnostic unit for compiling telemetry data, transmitted in real-time, of an engine and various parts of a vehicle, comparing the telemetry data with specific values of the engine and various parts to determine if there are any abnormalities in vehicle performance, and monitoring diagnostic results of vehicle performance; and a communications unit for performing communications in real-time through a network with an external user requesting vehicle performance diagnostic results of the diagnostic unit. Accordingly, the driver or external user may easily determine if there are abnormalities in vehicle performance, take steps to cope with vehicle malfunctions before they occur, and know the precise location of any abnormal areas of vehicle performance.