EngineMilesGas-only MPG and the dashboard average
A plug-in hybrid’s displayed MPG may reflect electric miles as well as gasoline use. Electric trips add distance without using as much fuel, so an overall average can look much higher than gasoline-mode fuel economy.
EngineMiles uses the vehicle’s gas-only fuel economy for its engine-mile estimate. Multiplying fuel by a combined driving average can overstate the gasoline-engine miles you’re trying to estimate.
MPGe is a different measure
MPGe expresses energy efficiency on a gasoline-equivalent basis. It is not the miles traveled for a gallon of gasoline burned, so don’t use it as gas-only MPG in EngineMiles.
Find a starting figure
Look for the gasoline-only or charge-sustaining fuel-economy rating for your exact model and year. In the US, FuelEconomy.gov’s vehicle comparison can help you find the appropriate rating. For other markets, check your manufacturer’s specifications or the relevant local rating source.
Check the units: US and imperial gallons differ. Metric fuel consumption commonly uses liters per 100 kilometers. Use the units selected for your vehicle in the app.
A rating is a starting point
Official ratings are estimates under specified test conditions. Real driving can differ. Your engine-mile result will change with the fuel economy you enter, so choose a figure appropriate to gas-mode driving and keep your assumptions consistent.