A TCU is a small computer in your vehicle that is able to report on nearly every detail — from speed and idling, to fuel use, low tire pressure, and more. This information can mean saving on maintenance costs by better monitoring vehicles or improving fuel efficiency by learning more about driving habits.   A vast amount of data can be processed and analysed with a telematics device and other connected hardware or sensors, such as: Position (GPS)  Vehicle speed Trip distance/time Idling time Harsh braking and driving Seat belt use Fuel consumption Vehicle faults Battery voltage, and other engine data.