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Computing the Fuel Consumption of your Vehicle
This is a fairly straightforward approach. Most vehicles do not have a fuel flow
sensor, therefore; you need to use the Mass Air Flow (MAF) sensor and the
Vehicle Speed Sensor (VSS) to calculate miles per gallon (MPG).

1. Mass Air Flow - The mass of Air in grams per second consumed.
2. Vehicle Speed Sensor - The actual speed of the vehicle.

For today’s vehicles and by EPA regulations vehicles use the oxygen sensors to
feedback data to the ECM and control the air to fuel
ratio. This ratio is set at the chemically ideal value
of 14.7 grams of air to every gram of gasoline.
Since we now have a quantitative value we can use
other known values to convert the MAF to Gallons
of gas per hour (GPH) and then calculate miles per gallon (MPG).
Here are the steps to make the conversion:
1. Divide the MAF by 14.7 to get grams of gas per second
2. Divide result by 454 to get Lbs gas per second
3. Divide result by 6.701 Gals gas per second
4. Multiply result by 3600 to get gallons per hour
The math expression for GPH is: MAF * 0.0805
The value for vehicle speed is delivered in Km/Hr, to convert to miles multiply by
0.621317. To calculate MPG divide the MPH by GPH. The final math expression
for MPG will be:
(VSS * 7.718)/MAF

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