Abstract: A system for interfacing with a vehicle broadly comprises a processing element, a memory element, a display, a user interface, a network port, a device port, and a vehicle interface unit. The processing element executes computer code or programs and is in communication with the memory element, which stores programs and data. The display presents information to a user. The user interface allows the user to interact with and enter information into the system. The network port allows the system to communicate with other systems or devices. The device port provides communication with a plurality of external components. The vehicle interface unit is coupled with the vehicle components and a plurality of batteries and is configured to determine a voltage level and a charge level of each of the batteries. The vehicle interface unit is alternatively coupled with the vehicle components and components of an engine to determine performance parameters.