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 measurement has been 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. But what is MPGe? 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?

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 in 2010, the Environmental Protection Agency came up with a way to compare different fuels based on their energy content — miles per gallon equivalent. Two new vehicles were on the market, the Nissan LEAF and the Chevrolet Volt, which didn’t fall into the normal window sticker calculation for miles per gallon.

How To Calculate MPGe

So how is MPGe calculated? To calculate miles per gallon equivalent, you first need to know the gallon gasoline equivalent (GGE). GGE was created by the National Institute of Standards and Technology in 1994 originally to help figure out the fuel efficiency of natural gas powered cars. Knowing the GGE gives us a common denominator for comparison of MPGe to MPG.

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. For example, if an electric vehicle can drive 75 miles using 33.7 kWh of electricity then the MPGe calculation is 75, or the same as a gas powered car that gets 75 MPG.

Here are a few modern electric vehicles and their official MPGe ratings:

• 2023 Audi Q4 e-tron – 103 MPGe (112 city/ 94 highway)
• 2023 BMW i4 eDrive40 Gran Coupe – 109 MPGe (109 city/ 108 highway)
• 2023 Cadillac LYRIQ – 89 MPGe (97 city/ 82 highway)
• 2023 Chevrolet Bolt EV – 120 MPGe (131 city/ 109 highway)
• 2023 Hyundai Kona Electric – 120 MPGe (134 city/ 106 highway)
• 2023 Kia EV6 – 117 MPGe (136 city/ 100 highway)
• 2023 Kia Niro Electric – 113 MPGe (118 city/ 107 highway)
• 2023 Lucid AIr – 140 MPGe (141 city/ 140 highway)
• 2023 Mercedes-Benz EQS 450 4Matic – 103 MPGe (101 city/ 105 highway)
• 2023 Nissan LEAF – 111 MPGe (123 city/ 99 highway)
• 2023 Porsche Taycan GTS – 83 MPGe (83 city/ 82 highway)
• 2023 Subaru Solterra AWD – 104 MPGe (114 city/ 94 highway)
• 2023 Tesla Model 3 – 131 MPGe (134 city/ 126 highway)
• 2023 Toyota bZ4X – 119 MPGe (131 city/ 107 highway)
• 2023 Volkswagen ID.4 – 107 MPGe (115 city/ 99 highway)

MPGe can vary based on vehicle design, weight, drivetrain efficiency, and other engineering factors just like a gasoline powered vehicle.

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. In that way it is just as useful as comparing MPG numbers for gas or diesel powered vehicles when shopping for a new ride.

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 NAPAOnline or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on alternative fuel vehicles and learning how is MPGe calculated, chat with a knowledgeable expert at your local NAPA Auto Parts store.

Photo courtesy of Flickr.

[cf]skyword_tracking_tag[/cf]