How to Calculate MPGe vs. MPG
The 2014 Accord Plug-In Hybrid enjoys a 124 city / 105 hwy MPGe rating.*
It’s no secret that vehicle gas mileage is a supremely important selling point for many cars on the market today. Here at Fisher Honda in Boulder, we’re very proud of the high fuel-efficiency ratings our current Honda models offer. For many customers looking to drastically decrease the amount of time they spend at the pump, a hybrid Honda vehicle is an ideal choice. However, fuel efficiency for hybrid models is calculated via miles-per-gallon equivalent (MPGe) instead of MPG. So how is this equivalent number calculated differently than normal MPG? First, let’s explore how a vehicle’s fuel efficiency number is obtained.
MPG and MPGe Testing
In order to find out how many MPG or MPGe a car gets, it must first undergo a series of tests by the Environmental Protection Agency, or EPA. Over the years, the EPA has shown that gas-powered vehicles receive a higher MPG on the highway than in the city, while electric and hybrid vehicles actually get better mileage ratings in stop-and-go city situations. Models manufactured in 2008 and later undergo tests with five different factors in a controlled environment. However, the EPA only tests about 10% to 15% of all models in production, so automakers are trusted to provide their own honest results. But, the EPA does make an exception for electric vehicles and plug-in hybrids, as they test every new EV and PHEV on the market.
What’s the Difference Between MPG and MPGe?
A vehicle’s MPG rating is fairly self explanatory. It’s the number of miles your car can drive per gallon of gas. Figuring out an MPGe rating is a little more complicated. Since engines that use an alternative source of fuel can’t be measured by liquid gallons of fuel, the MPGe rating is calculated by figuring out the number of miles a vehicle can go using the same energy content as a gallon of gas. The EPA calculates that 33.7 kilowatt-hours of electricity is the equivalent to one gallon of gas, so an electric or hybrid vehicle that uses 29 kWh per 100 miles would get a combined 115 MPGe rating.
Spend More Time Driving and Less Time Filling Your Tank
If you’re interested in exploring our selection of hybrid Honda models, feel free to contact our sales associates at (866) 826-7340 to schedule a test drive! Otherwise, visit our dealership at 6025 Arapahoe Road in Boulder to browse our showroom at your convenience.
*115 combined miles per gallon of gasoline-equivalent (MPGe) electric rating; 47 city/46 highway/46 combined MPG gasoline only rating. 13 mile maximum EV mode driving range rating. 570 mile combined gas-electric driving range rating. Ratings determined by EPA. Use for comparison purposes only. Your MPGe/MPG and driving range will vary depending on driving conditions, how you drive and maintain your vehicle, lithium-ion battery age/condition, and other factors. For additional information about EPA ratings, visit https://www.fueleconomy.gov/feg/label/learn-more-PHEV-label.shtml.
8 comment(s) so far on How to Calculate MPGe vs. MPG
why can’t dealers tell you how many miles per charge? if you say you get 98 MPGe then you can’t drive from the Valley in Oregon to the coast and back without having to recharge for around 7 hours. so why buy one?
PHEV are designed to provide an “all-electric” daily commute. Longer trips start out on battery then transition to hybrid gas/electric. No need to find a charger or wait. Our PHEV (Chevy Volt) goes for months without using any gas. On long trips it gets good MPG as a gas/electric hybrid. Local commuting is the optimum use but it does offer hassle-free distance driving.
Why wasn’t it just calculated to MPK Miles Per Kilo-watt? Then the government could attach the ~$0.85/gallon fuel tax onto the kwh charge during recharge and generate additional road and bridge funds. Which, these vehicles contribute $0.00 to currently yet still use the infrastructure!
Actually, EVs and PHEVs do contribute to the road and bridge funds thru the $150-$300 per year tax that is added on to our annual registration fees. In Washington as of September 2019 EVs and PHEVs will be charged an additional $225 when renewing our license tabs. Also, because most real EV owners charge their cars at home, there is currently no reasonable way to separate the kWh used by the car from the kWh used by the normal household. Unless there is a separate meter installed in the circuit used for charging there would be no way to tax the power.
Thank you for trying to explain MPGe, but there are at least two puzzles: 1) is 33.7 kWh the actual energy content of a gallon of gasoline based on complete combustion, or is it the amount of useful work an average gasoline-powered vehicle manages to extract from one gallon? 2) I don’t see any city versus highway MPGe ratings, so apparently it describes a vehicle just cruising along at a steady speed. But in city stop-and-go driving, or up and down hills, braking recovers some of the energy. So is real-life MPGe higher than the EPA rating?
How much coal, natural gas, or petroleum is used to generate a kilowatthour of electricity? US Energy Information Administration
The average number of kWh generated per amount of, petroleum liquid fuels consumed by the U.S. electric power sector for electricity generation in 2020 were: Petroleum liquids–12.76 kWh/gallon
Example: Tesla Model 3 25 kWh/100 miles (US dept of energy)
or .25 kWh per mile thus: 12.76 / 0.25 = 51 mpg.
Are you guys for real, gasoline is a hydrocarbon compound, 13% hydrogen and 87% carbon 100÷(29÷33.33333) =114.95 miles per kilogram of hydrogen to calculate miles per gallon you need to add carbon to the hydrogen ( 0.87÷ 0.3714919 = 2.3419 ) gallons of gasoline. Now dividing by gallons 100÷2.3419=42.7 This is the real MPGe. The EPA is wrong. Apparently they don’t know that gasoline contains carbon.
Hey, dude are we the only two people on the planet who know this, or are there others.