DTE/Average Fuel Economy (AFE)

WARNING: This page is about a different car, the 2018 Ford F-550 Super Duty, 2018 Ford F-450 Super Duty, 2018 Ford F-350 Super Duty, and 2018 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.

The DTE is calculated in the IPC using the Running Average Fuel Economy (RAFE), which is the fuel economy over the last 480 km (300 miles), and the fuel level input from the fuel sender(s) to determine how many miles the vehicle can be driven based on the remaining fuel in the tank. The DTE can vary in the short term by up to 50 miles, but is usually within 10 miles. Even if the fuel economy is relatively constant, the DTE can be off over a 50 mile range by -24% to +38%. The DTE display and the fuel gauge both use the fuel level input from the fuel tank to provide their respective functions. If the fuel gauge doesn't function correctly, both the fuel gauge and the DTE display are affected.

The IPC defaults to around 18 mpg when the battery is initially connected and changes based on driving habits and conditions. Generally, the driver should be getting somewhere between 13-21 mpg.

NOTE: The actual DTE can be higher or lower than the DTE displayed in the message center due to changes in driving conditions. It is important to understand how the DTE is calculated and the factors that impact the DTE display when determining how to address any DTE concerns.

Since the DTE is calculated and averaged over a longer period of time (480 km [300 miles]), varying driving conditions can have a significant impact on the current or short term DTE as opposed to the displayed DTE. This difference often leads to customer complaints of incorrect or invalid DTE. The following list provides some (not all) of the driving conditions that may lead to an incorrect or fluctuating DTE concern:

Changing between towing/not towing
Changing driving between city and highway
Allowing the vehicle to idle for long periods of time
Using the remote start feature frequently to allow the vehicle to warm up, particularly when parked on a grade
Parking or driving on grades
Inconsistent use of gasoline or E85 fuels
Over-fueling or not filling the tank completely (partial refueling)

To better illustrate the affects of how driving conditions can affect DTE, refer to the following 2 examples. The first example below illustrates how the following observations are normal and expected since the low fuel reminder is triggered from a fuel volume and not from a fixed distance to empty.

If while driving, the low fuel reminder (low fuel indicator and low fuel warning message) displays when the DTE equals 94.4 km (59 miles) and the driver adds 11.36 L (3 gallons) of fuel, the new DTE may become 124.8 km (78 miles). After continued driving, the low fuel reminder may now display when the DTE equals 83.2 km (52 miles).

The second example (below) illustrates what occurs when idling on an incline. In this example, the customer should be made aware of how the condition will correct after a few minutes of idling on a level surface.

If the customer stops and parks the vehicle on an incline in a driveway, then in the morning remote starts the vehicle, allowing the engine to idle, the DTE may now equal 184 km (115 miles). As the customer drives, the low fuel reminder displays when the DTE equals 148.8 km (93 miles). Finally, after 5 more minutes of driving, the DTE is back to 80 km (50 miles).

The IPC uses the following network messages to control the DTE/Average Fuel Economy (AFE).

Fuel alcohol percent
Fuel flow volume display
Odometer count
Transport mode

The IPC receives all messages from the GWM over the HS-CAN3. The GWM receives the transport mode message from the BCM over the HS-CAN1. The GWM receives the fuel alcohol percent, fuel flow volume display and the odometer count messages from the PCM over the HS-CAN1.