electric car

MPGe — A New Fuel Economy Measurement?

There are many ways to compare vehicles, such as power or efficiency. For over 100 years, fuel economy has been measured in terms of miles per gallon — the distance you can travel using one gallon of fuel. When comparing two vehicles, it’s easy to see that a 30-mpg vehicle will use more fuel than a 45-mpg vehicle. You can even use mpg to determine how well you’re driving or how well your engine is running by simply dividing your mileage by how much fuel you use.

With alternative fuel vehicles came the introduction of a new fuel economy measurement — MPGe, or miles per gallon equivalent. This measurement is used for plug-in hybrid electric vehicles, extended-range electric vehicles and battery electric vehicles (PHEV, EREV, and BEV), as well as hydrogen fuel cell vehicles, compressed natural gas vehicles and liquefied natural gas vehicles (HFCV, CNGV, and LNGV). How can you possibly compare fuel economy among these vehicles? That’s where MPGe comes in.

What Exactly Is MPGe?

MPGe - Making Sense of a Unlike regular gasoline-powered internal combustion engine vehicles, plug-in vehicles use rechargeable battery packs for part or all of their motive energy. This presents a bit of a problem when it comes to comparing fuel economy, because gasoline and electricity aren’t measured in the same way. Gasoline and diesel are measured in gallons, while electricity is measured in kilowatt-hours (kWh). The fuel economy of plug-in vehicles is therefore measured in kilowatt-hours per 100 miles (kWh/100mi).

Comparing the energy usage of vehicles with dissimilar fuel sources is a challenge. To address it, the Environmental Protection Agency came up with a way to compare different fuels based on their energy content — miles per gallon equivalent.

To calculate miles per gallon equivalent, you first need to know the gallon gasoline equivalent (GGE). For plug-in vehicles, 33.7 kWh of electricity is 1 GGE, and for hydrogen fuel cell vehicles, 1 kg H2 is 1 GGE. Next, you simply calculate how far the vehicle can travel on 1 GGE.

How Can You Use MPGe?

Now you know what MPGe is, but what can you use it for? It’s not like you can use it to compare how much it will cost to refuel or recharge, because these numbers don’t translate to anything useful. You can, however, compare the efficiency and environmental impact of different vehicles that use alternative fuel before making a purchase decision.

Whether you already own one or you’re looking into buying an alternative fuel vehicle, how much energy you really need to get from place to place might surprise you.

Check out all the Fuel & Emission System parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on alternative fuel vehicles and MPGe, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

about author

Benjamin Jerew

Ben has been taking things apart since he was 5, and putting them back together again since he was 8. After dabbling in DIY repairs at home and on the farm, he found his calling in the CGCC Automobile Repair program. After he held his ASE CMAT for 10 years, Ben decided he needed a change. Now, he writes on automotive topics across the web and around the world, including new automotive technology, transportation legislation, emissions, fuel economy and auto repair.

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