A diagnostic tool for diagnosing a vehicle in various environments, comprising: a processor configured to control functions of the diagnostic tool and retrieve diagnostic data from the vehicle; a first memory connected to the processor and configured to store a software to operate the diagnostic tool and wherein the processor is configured to store and overwrite the retrieved diagnostic data in a circular buffer in the first memory; a connector interface in communication with the processor and configured to connect the diagnostic tool to a data link connector in the vehicle, the connector interface being configured to communicate with the processor; a serial communication interface between the processor and the connector interface, configured to allow the diagnostic tool to communicate with the vehicle in at least one communication protocol; a power management unit configured to detect changes in the diagnostic tool's external temperature environment and manage the diagnostic tool in various power states defining a plurality of operating modes, the operating modes including a normal operating mode and at least one power saving mode, depending on the diagnostic tool's external temperature environment and the diagnostic tool's activity; a trigger button configured, when pressed by a user, to cause the diagnostic tool to change from the at least one power saving mode to a normal operating mode, if the diagnostic tool is in the at least one power saving mode, wherein the normal operating mode comprises retrieving diagnostic data; a capacitor configured to provide power to the diagnostic tool; a capacitor charger configured to charge the capacitor at a constant power, a second memory configured to receive diagnostic data and wherein the processor is configured to transfer the diagnostic data from the circular buffer into the second memory on occurrence of a trigger event; and a preconfigured filter configured to filter the diagnostic data to preclude irrelevant data from being stored in the circular buffer. a processor configured to control functions of the diagnostic tool and retrieve diagnostic data from the vehicle; a first memory connected to the processor and configured to store a software to operate the diagnostic tool and wherein the processor is configured to store and overwrite the retrieved diagnostic data in a circular buffer in the first memory; a connector interface in communication with the processor and configured to connect the diagnostic tool to a data link connector in the vehicle, the connector interface being configured to communicate with the processor; a serial communication interface between the processor and the connector interface, configured to allow the diagnostic tool to communicate with the vehicle in at least one communication protocol; a power management unit configured to detect changes in the diagnostic tool's external temperature environment and manage the diagnostic tool in various power states defining a plurality of operating modes, the operating modes including a normal operating mode and at least one power saving mode, depending on the diagnostic tool's external temperature environment and the diagnostic tool's activity; a trigger button configured, when pressed by a user, to cause the diagnostic tool to change from the at least one power saving mode to a normal operating mode, if the diagnostic tool is in the at least one power saving mode, wherein the normal operating mode comprises retrieving diagnostic data; a capacitor configured to provide power to the diagnostic tool; a capacitor charger configured to charge the capacitor at a constant power, a second memory configured to receive diagnostic data and wherein the processor is configured to transfer the diagnostic data from the circular buffer into the second memory on occurrence of a trigger event; and a preconfigured filter configured to filter the diagnostic data to preclude irrelevant data from being stored in the circular buffer.