The apexi i-cruising connects to your odb2 port and monitors a number of essential engine metrics related to fuel economy. odo (total distance), trip (distance interval) of each fuel, fuel use and amount of fuel consumption are all recorded and fed back to the driver so they can make educated assumptions about their driving styles. to gain the most accurate estimates, the driver can even adjust for the tire size/diameter and the real-time data display can simultaneously display multiple data and peak values.