Disclosed are systems, methods, and non-transitory computer-readable media for testing and characterization of computing systems implemented in vehicles. A testing system causes packet injectors in a vehicle networking system to execute a testing mode in which the packet injectors transmit synchronized sequences of data packets within the vehicle networking system. The testing system gathers, from logging mechanisms located within the vehicle networking system, diagnostic data describing data packet transmissions in the vehicle computer network during the testing mode. The diagnostic data includes data identifying data packets detected by the logging mechanisms and timestamps indicating times at which the data packets were detected by the logging mechanisms. The testing system generates, based on the diagnostic data and an expected diagnostic data, a testing report describing performance of the vehicle networking system during the testing mode.