2008 Subaru Outback Owner's Manual - Page 127

3-8 Instruments and controls We recommend that you drive moderately until the pointer of the temperature gauge reaches near the middle of the range. Engine operation is optimum with the engine coolant at this temperature range. And high revving operation while the engine is not warmed up enough should be avoided. & ECO gauge NOTE . The ECO gauge shows only an approximate indication. . After resetting the trip meter, the average rate of fuel consumption is not shown until driving 0.6 mile (1 km). Until that time, the ECO gauge does not operate. CAUTION If the pointer exceeds the normal operating range, safely stop the vehicle as soon as possible. Refer to "In case of emergency" in chapter 9. The ECO gauge shows the difference between the average rate of fuel consumption and the current rate of fuel consumption. Using the average rate of fuel consumption since the trip meter was last reset, if the current rate of fuel consumption is higher than the average rate of fuel consumption, the indicator needle points to the "+" or right side, and if the current rate of fuel consumption is lower than the average rate of fuel consumption, the indicator needle points to the "−" or left side. When the indicator needle is pointing to the "+" or right side, it indicates fuel-efficient driving.