Why America's MPG Is A Dumb Unit For Fuel Economy
Miles Per Gallon (mpg) is a dumb unit we use in the United States.
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In the United States, we measure fuel economy with miles per gallon (mpg), rather than gallons per 100 miles, or liters per 100 kilometers. Using distance per volume of fuel consumed causes a rather weird scenario for comparison purposes however, which is perhaps why the rest of the world does the reverse: volume of fuel consumed per distance driven. Enjoy the video to see how the math causes complications with MPG that don't exist when using G/100mi or L/100km.

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  • Engineering Explained
    Engineering Explained

    If you enjoy watching me throw gallon jugs, you'll love this video: fibill.info/nick/videot/s3WpqZKrZGl0iak

    • zefallafez

      How many white boards per marker do you get, or is it white boards per 100 markers?

    • Tyler Wood
      Tyler Wood

      You should just use gallons per hour. It's way more accurate

    • Mark Hackett
      Mark Hackett

      @babybirdhome Nobody cares how many gallons it will take them to go on vacation either. They fill the tank and look at the cost.

    • Greybone62

      The Danes, uses, as far as I know, distance obtained by given volume of fuel.

    • Василий Мельник
      Василий Мельник

      @Žluna Zelená you mean "20 miles per buck"? Otherwise you sound like if 'murica switched to metric. I'm also impressed you got the bucket volume right.

  • renragged

    Scenario 2 and sell the 5mpg vehicle.

  • Rdd Sknk89
    Rdd Sknk89

    I’m sorry, but you didn’t say anything in this video to convince me that gallons/100 miles is better than MPG. For a person with single car, there’s no reason to calculate it any other way then MPG. If you know the distance you want to travel, and you know your fuel economy, divide distance by fuel economy, and then that’s how much fuel you need. No need to faff around with multiple calculations figuring it out the other way. And on the point of going from 5 to 6 MPG being bigger than going from 50 to 51… well yeah, obviously. It’s the same absolute increase, but a much different relative increase. Even if people don’t know how to put it into technical terms, I think most understand that intuitively. For a person with one or two cars, bigger MPG=better, end of story. And calculating how much fuel you need for a trip is much easier. And it’s not like a genie is going to pop out of a bottle and ask if you want to increase the MPG of your Prius or your gas-guzzling Hummer. And honestly, if that did happen somehow, I think most people would still increase the one with worse MPG. Absolutely no reason to deal with gallons per 100 miles. Lastly, in my opinion, MPG is just more elegant. That’s just aesthetics, but still.

  • Arnie Geddon
    Arnie Geddon

    Extremely long winded example of the law of diminishing returns.

  • PandaMan

    you're using a theoretical/magical doubling of fuel economy scenario to justify why gallons/mile is better than miles/gallon when the two concepts don't care about the other.

  • Hamidreza Saberyoun
    Hamidreza Saberyoun

    FINALLY somebody said it 🤣

  • Kasper Guldmann
    Kasper Guldmann

    Can you do a video on MPGe? Also, can you show what a gallon of e looks like?

  • max factor
    max factor

    MPG is not normalized.

  • patriot 945
    patriot 945

    This will become relevant when fuel stations are 100Km apart, so we can pretend we are all engineers, and throwing gallon jugs looks fun. Would you throw 5 1 liter jugs to simulate an imperial gallon. Have a fun day.

  • James Daniel
    James Daniel

    Miles per gallon doesn't measure efficiency except in one direction. An engine can be efficient in producing more power per volume of fuel used or it can be measured in the amount of fuel used to travel a given distance. The latter is affected by the terrain, the weight of the car, the weight of passengers and cargo, etc. Output is only affected by temperature and air peressure as an uncontrollable issue and air pressure can be controlled with a turbo or a supercharger.

  • Hemant Jadhav
    Hemant Jadhav

    Its lot easier if we use cents/mile!

  • Asif Kidwai
    Asif Kidwai

    Very interesting math in this video. File away in the Nerd/Geek box, but still useful to everyone. Disclaimer: if complicated math gives you a headache, take your advil before watching this video.

  • Maya Jane
    Maya Jane

    now do it with 9 cars that only get 15 mpg and one car gets the 5 mpg and see what you come up with

  • Rim Fire
    Rim Fire

    What's even dumber? THE WHOLE IDEA THAT YOUR SCENARIO IS BASED ON DOUBLING SOME VEHICLES MILEAGE. Even 20% is a rather dubious scenario.

  • shrekviper01

    Come on. If you can double the mpg on 9 cars, I'm sure you could find the funding to double the 10th car too.

  • Hellion “Hellion1” 1
    Hellion “Hellion1” 1

    Here we live by Litres\100km.

  • talyf coelho
    talyf coelho

    Just do like brazillians: we use Km/L lol

  • J Sh
    J Sh

    You made a mistake with your math there in the beginning. See scenario 1 vs 2 in your whatever diagram

  • j m
    j m

    So basically, don't have any vehicles in your fleet that gets 5 mpg.

  • Henge

    For me its more important with the quality of the content then the saneness of the units :)

  • Nathan Spain
    Nathan Spain

    I only have one car though so.....

  • Lurking Turkey
    Lurking Turkey

    L per 100km works

  • Brett Blose
    Brett Blose

    The problem is that it is highly unlikely that all vehicles will get the same amount of usage and are interchangeable. It doesn't factor in that the 5 mpg vehicle may get lower mileage because it is larger and can haul what the others can't. Or alternatively if they can be used interchangeably it is highly unlikely that some of the usage of the 5 mpg vehicle couldn't be shifted to the now 100 mpg vehicles. But yes MPG isn't that intuitive but it is an accurate way to measure fuel consumption.

  • Mark Jones
    Mark Jones

    Literally every standard of measurement that we have here in the U.S. is flipping horrible compared to the brilliant metric system that the rest of the world uses. We need to adopt that system.

  • Sephiroth5200

    If you have a vehicle that can display both values, like mine, you can use both. My truck averages 18.4 mpg or 13.4L/100km. I digress though. I live in Michigan. We measure distance with time and fuel economy with money. For example: Grand Rapids is 90 minutes away and costs me $20 in fuel on the old highway. It is 70 minutes and $30 to take the interstate.

  • Cam Bryan
    Cam Bryan

    Because REAL Americans measure in Smiles per gallon anyway. Self explanatory.

  • tinker'n e-round
    tinker'n e-round

    I've been doing this for years. I'm a large vehicle transporter who pays for my own fuel. Slowing 10 mph can bring me from 5 mpg to 7 mpg moving two boomed together tractors where when I drive my 3.6 l Buick car I only go from 32 mpg to 38 mpg dropping the 10 mph. If a person put a value on their time the fuel savings slowing 10 mph is negligible in a modern car, but substantial in a big truck. I once moved a new trash truck from Iowa to Florida. It took me 3 extra hours to get there by slowing to 55 mph. I saved $100 in fuel on the trip. $33.33/hour for the extra hours...

  • Trustin Judo
    Trustin Judo

    I just like mpg because its way easier and faster to say than L/100km. I really wish my truck was in mpg

  • Black Conservative Patriot
    Black Conservative Patriot

    I love this channel BUT totally disagree. When I was 16 and needed to put gas in my parents' car, I needed to know how much $$ I needed to hang out with my mates or take a girl on that date and it was hardly 100 miles round trip. But MPG let me budget a lot better!

    • Aonodensetsu

      well if you have G/100 then you can just literally divide 2 G/100 means you use 2 gallons per 100 miles so for 10 miles, which is 10 times less distance, you use 10 times less fuel, so 0.2 gallons

  • Aaron Peplinski
    Aaron Peplinski

    Diminishing returns. MPG is easy to calculate at fuel up. This is a good measure for keeping up on the health of your vehicle/ let you know if your driving habits are costing you money.

  • MrDannyd9

    The percentage gained is higher on the lower numbers

  • Critical Error
    Critical Error

    You forgot to remove 'mpg is a' in the title.

  • Telhmaaa

    It does not matter if you do this in MGP or liter/100km, because distance is your breaking point. I am not used to MPG, so i had to convert it to L/100km, so i took 5L/100km and 50L/100km. if you do the same calculation in line 2, you get avarages of 7,25L/100km for the first set of cars, and 7L/100km for the next set of cars. So yea, senario 2 would in this case look better. but, if all cars would only drive 50km. then the first senario is better. because then you would have used 36,25 Liter for the first fleet, and 35L for the second fleet ;)

  • Klaus Schroiff
    Klaus Schroiff

    Must be cool being in the same boat as Myanmar and Liberia ... (although the two want to abandon it)

  • Mick Orange
    Mick Orange

    What is the average area for each scenario? (Miles/LxWxH)

  • Warwick Penn Bradly
    Warwick Penn Bradly

    Why the hell USA hasn't let go of imperial units, I'll never know. Metric is better in just about every circumstance.

  • geoffrey ethelston
    geoffrey ethelston

    One of my vehicles is large truck, so I tow 4 of the cars and I sell the other ones and and not worry about it

  • Cobb

    If you can afford to drive and maintain a personal 10 car fleet, you can afford the gas regardless. Also, it depends on which of those 10 cars you drive the most on which scenario is best, if that 5 mpg car is just the Sunday fun car then it's better to double the mpg of the cars you drive the rest of the week. The other option is to just sell the 5 mpg car and not have a problem.

  • Jonathan Mayer
    Jonathan Mayer

    If you have 9 vehicles in your fleet with 100mpg, you just don't drive the 10th car. Boom, savings. This comment is meant to be a joke, but seriously who wouldn't sell off that 10th vehicle for maybe another 100mpg one? Or just make due with 9 vehicles.

  • Ellis FourThirty
    Ellis FourThirty

    My car gets 40 rods to the hogs head, and that's the way I likes it!

  • homfri

    now we just need to figure out the Subaru math and figure how many head gaskets per 100 miles

  • casey m
    casey m

    By the way, the car that gets 5 mpg that he was referring to is a top fuel dragster with a 3000 hp engine.😆

  • James Oldman
    James Oldman

    When calculating how much fuel I need for a trip I find it easier to use L/100. Just seem to be nicer figures to work with

  • Ethan Forsyth
    Ethan Forsyth

    Just use light years per miles (A light year is the distance light travels in a year. Measurement system)

  • gee Tee
    gee Tee

    ~5.15ish law of diminishing returns

  • Yasha Baral
    Yasha Baral

    I literally didn't understand a thing you said. I'm super confused.

  • paul kelly
    paul kelly

    MPG is a measure of cost. People know how much they pay per gallon, and the more miles the car goes on that gallon, the lower the direct operating cost per mile.. duh. The real farce is eMPG or MPGe.... It is in no way a measure of cost to operate or even an equivalent to MPG. You see numbers like 100 MPGe... so WOW, it must be way cheaper to operate than a gas car... wrong. The electric equivalent to MPG, would be kw per mile. An Audi Etron gets about 2.1 miles per Kw. Charge America charges .46 cents per Kw, so.. about 22 cents per mile to run the eTron.. so, dividing the current cost of gas at 2.90 by .22 or gas equivalent of 13.2 MPG, but the Government gives the eTron a rating of 74 eMPG.. surprise!

  • Rudolph Guarnacci
    Rudolph Guarnacci

    Love it or leave it. 'Murica

  • Ananay Joshi
    Ananay Joshi


  • David Walls
    David Walls

    Given I plan to keep my car for more than 100 miles I want to know how far I can drive before I need to fill up. If my car gets 31 MPG and I have a 15 gallon tank I can easily calculate I can get 465 miles on a tank of gas. If you say I can get 100 miles on 3.2258 gallons of gas (same MPG) the math for a 15 gallon tank is not so simple.

  • wasif syed
    wasif syed

    your math in scenario 2 is wrong it is 1.1 gallon per 100 miles not 2.9 gallons

  • jeanpeup

    It makes sense to use mpg in a place where gas is cheap and you only care about how far the car will get you. L/km makes more sense in Europe where gas is expensive and you want to know more about how much it will cost you to use your car.

  • Waldemar Ishibashi
    Waldemar Ishibashi

    It's the same nonsense in Japan. km/l

  • bwillan

    The distance per volume for fuel economy is a much easier calculation (trip odometer reading for distance and volume off the fuel pump). Also it is also a bigger is better unit. The volume per fixed distance is harder to wrap your head around and is harder to calculate.

  • S E
    S E

    As a truck driver I find mpg to be weird, because it doesn't account for weight. Obviously, you will burn more fuel if you weigh 105,000lbs than if you weigh 26,001lbs. A straight mpg rating won't tell you which truck is most efficient for your purpose.

  • Dan K
    Dan K

    For tanks it's Gallons per Mile

  • Con Cahill
    Con Cahill

    This one I could't watch to the end. Had this conversation too many times before. And agreed to DISagree.

  • Nick Henderson
    Nick Henderson

    Interesting take on the topic, I didn’t realize that people might not think about this the same way that you and I do. I much prefer mpg though as it just sounds cleaner and is easier to say. The most important thing to realize is the concept of diminishing returns, which people that think like you and I think about at a subconscious level to begin with. I wouldn’t say mpg is a pointless measurement at all, but I can see the case for it being misleading at times

  • Cypherius Cain
    Cypherius Cain

    To be fair, while the official way of measuring fuel efficiency in Europe is l/100km, it is also very common to use km/l here. It's so common, in fact, that used car websites use it most of the time. So this isn't a USA problem😊

  • sue neil
    sue neil

    No surprise that the entire rest of the world is kilometres... or 6/10ths of a mile ... ahead of the US. Again.

  • QemeH

    The only reason the US meassures fuel consumption in distance per fuel amount instead of fuel amount per distance like almost every other country does is because the average american is incapable of understanding anything other than: *Bigger number better person* 'Oorah!

  • Lex Gso
    Lex Gso

    As most people don't have fleets of cars that travel all the time it is easier to calculate with MPG, as for businesses that have fleets it isn't a problem as they have a person who can easily convert for any particular need. Just my 2 cents.

  • James Spence
    James Spence

    Gotta love an "engineer" who uses semantics to hide values and reinforce his own argument like it means something. When used for consumer average calculation MPG works just fine and the number crunchers in corporations use a different "metric" (see what I did there??) to calculate consumption for a reason. Anyone who "NEEDS" to be aware of this is aware of this or not qualified for the job they're in. Not MY problem and neither are you. Wont be back to this channel for that reason. If you ever stop trying to manipulate your audience let me know, I'll come check you out again.

  • Chomp

    That reminds me that the standards for weight in the US is actually metric, i.e. Kilogram. All scales are actually calibrated to that. When we switched over to L/100km in Canada, it was weird. But once I got my head around it, it was actually easy to understand.

  • Father Guido Sarducci
    Father Guido Sarducci

    I need to remember this video for the next time I can’t sleep.

  • John Mills
    John Mills

    what really blows my mind is that a US gallon (=3.79 L) is not the same as a UK gallon (=4.55 L) . Puleeeze !

  • Otso Kivivuori
    Otso Kivivuori

    This is a bit of a mistargeted argument dealing with large fleets of cars, while the average viewer probably has at most 2, more likely 0 or 1. The better argument, i think, is that the driver in almost all cases has a predetermined target they are driving to. Say you are driving to your parents', who live 200km away (or 200 miles, doesn't matter) and you have a car that can do 10l/100km. Then you need 20 liters of fuel for the journey. It is almost never the case that you think "I'll tank up 30 liters and just drive as far as that takes me". Ergo, the volume/distance measurement is better. Bonus point: the v/d measurement simplifies nicely to area, while the other way only goes to 1/a, which while not really relevant to this is something my mathy brain enjoys.

  • Conor Graaf Pietermaritzburg South Africa.
    Conor Graaf Pietermaritzburg South Africa.

    For the love of God change to Metric!

  • nikolygtx

    i wonder if Usa didn't steal land and everything else would they this big at all

  • C Rutherford
    C Rutherford

    Interesting stuff, Beto!

  • Tobber FU Too Again!
    Tobber FU Too Again!

    Foolish comparison. The wallet over the lifetime of a car determines efficiency.

  • Max G.
    Max G.

    is no one going to bring up 0:46-0:48? that jump cut w/ the audio of the jug hitting the floor was pretty funny :D

  • eric moss
    eric moss

    This is like complaining about miles per hour because computing average speed over multiple segments is a bit tricky. MPG makes all the sense that it needs to for the driver.

  • Michael Hawes
    Michael Hawes

    The whole US system of weights and measures is a joke. That's why nobody else uses it. I think it's pointless to try to introduce a logical improvement such as Jason suggested, into a system that's a complete mess anyway.

  • Agent gumshoe
    Agent gumshoe

    Jason i gota diesel. Hook me up bro lol.

  • Travis Robertson
    Travis Robertson

    I like to calculate my cost per mile. My truck cost me, on average, about 13 cents per mile. (I understand that prices for electricity vary around the country as does the cost of diesel and gasoline, so the same vehicle will cost more or less depending on those variables.)

  • stephen watkins
    stephen watkins

    all this hypothetical calculations about what happens if you could double a cars mpg is nonsense a car can only do a certain mpg! if you measured the mpg of a certain car in the US and then calculated the mpg here in the uk it would have better mpg because USA are the only country in the world not to use the Imperial gallon which is larger tan the US gallon! I admit that here in the UK our system is mixed up we are supposed to be metric but we buy our fuel in litres but measure the distance between towns in miles! so people like to calculate how many gallons they buy then use that to calculate MPG

  • p739

    They have to use L/100km because km/L would be less than 1 most cases and make it look even worse than 5mpg. It should really be measured in L/hr or gal/hr. It makes more sense because when stuck in a traffic you are still using fuel and putting wear and tear on the engine and transmission without actually moving. All vehicles should also come with an hour meter coupled to engine speed in them

  • Jonathan Chen
    Jonathan Chen

    It's clearly not ideal for aggregate comparisons of fuel economy. But MPG actually makes sense in the context of marketing (bigger number means better), and works fine for consumers making direct comparisons between two or more vehicles. The same applies for miles per hour as well. Actually in that case, putting the miles on top is even more of a detriment, IMO, since you're more likely to be counting minutes left to an appointment than gallons left to empty, though nowadays we have ETA in navigation apps/systems and 'miles remaining' indicators to help with both.

  • John Runyon (DimeCadmium)
    John Runyon (DimeCadmium)

    Okay, but why would 1 car be driven the same total distance as 9 cars?

  • mushroomsteve

    Also, the density of gasoline changes a lot with temperature, so a gallon of gasoline at 85F is less gas than a gallon at 32F.

  • Mr CH11LER
    Mr CH11LER

    Meh, here in the UK we also use MPG. I will still get joy from rubbing it in my friends faces that my car averages 57mpg and will often get 68+mpg on a long trip.

  • Jay Bee
    Jay Bee

    yah... think $ per mile would be more useful. or... just drive a model 3 and then you can afford to drive.

  • thatjokerperson

    i mean i would rather know how far my car can go on a gallon than how many gallons it takes to go a distance

  • SalaCommander26

    Well it depends on how you're using the cars. If you want to drive each of the ten cars 100 miles, then yes, the second option is better. But if you're filling up all ten cars with gas and driving each of them until they run out of gas (or almost run out), then the first option is much, much better.

  • mos ab
    mos ab

    What if we had to buy miles instead of gallons?

  • Winston Smith
    Winston Smith

    But America went to the moon, so…

  • Austin Duke
    Austin Duke

    I measure my fuel in rods to the hogshead and that's the way I like it.

  • freakied0550

    I'll keep this in mind when I have 10 cars that all need to travel the exact same distance on a regular basis.

  • Brent Fraliex
    Brent Fraliex

    Wouldn't MPG be a metric not unit?

  • Emmett Thompson
    Emmett Thompson

    Try having an intermixed fleet and compare. You have unleaded, CNG, LPG, and Diesel. Each one of these vehicles gets a different MPG but it makes no difference as the cost of the fuel is quite different. CNG gets really wild as you need to figure the cost of compressing the fuel (electricity) to get it in your vehicle. All of these fuels have a different BTU rating. The best way I can compare is to calculate cost per mile (or cost per 100 miles). Throw in another problem is when you also own the station that delivers the different fuels..... i.e. infrastructure. Infrastructure can get quite expensive. Crunch in your cost per mile, figure what the up-charge for the vehicle engine and work that out, then what it cost to build the station and then you can come up with your ROI. Chances are you will lose on everything but diesel. diesel has the highest BTU rating of all and cost just as much to build the infrastructure as unleaded. CNG is cheap but you will never get your ROI for upcharges and infrastructure....never. Ahhhh, but you can feel good that you are using an alternative fuel!

  • Neo Getz
    Neo Getz

    My bike is the worst of both worlds. Instead of miles per gallon I can have miles per litre.

  • C Thorno
    C Thorno

    Metric looks like this 1 tonne = 1000 kgs 1 kg = 1000 grams 1km = 1000 meters 1 meter = 100 centimeters 1 litre = 1000 milliliters Imperial looks like this... 1 mile = 5280 Feet 1 foot = 12. Something Inches?? 1 pound =16 ounces... Nothing is perfectly divisible..why does the U.S. continue to use it??

  • winja

    you worked way too hard to try and trash MPG, but it was a complete miss. fuel economy is measured on how far a car can go on its allotted amount of fuel. large trucking fleets use this as most trucks get the same MPG. using any other measure is really irrelevant. in other countries where liters and kilometers are used thats the standard but they can still quote you the MPG of the car as well. its great at predicting range of the vehicle and can easily be used to estimate when and where you will need to fuel the vehicle. in the transportation industry that is worth its weight in gold. its far easier to literally anyone to figure out how far the can go with MPG. i dont have to do any complex math. i have a 20 gallon tank and i get 30 mpg. thats 600 miles. start looking for fuel stops in the 500 to 550 mile range.

  • Matt Wells
    Matt Wells

    Its just two different ways of figuring and interpereting the same information. If you need to figure out what your total fuel usage is amongst a fleet of vehicles, you have to do the math yourself lol

  • ludger will gaster
    ludger will gaster

    Tesla with bumper sticker...could of had a v8

  • ludger will gaster
    ludger will gaster

    Or sell the gas hog...and get 9 cars that do 100 per gallon and no bad ones

    • winja

      no..no no no no!!

  • Midi Man
    Midi Man

    It used to be when you purchased a new car the MPG was very close to the MPG sticker. Now a days the EPA is a big lie.

    • winja

      the funny thing is i purchased a "muscle car" and it gets way better fuel economy than the epa says it should. then i tuned it, now its faster, gets even better economy and thats illegal for some reason.....

  • MegaGouch

    0:32 that's not a gallon, it' a US gallon. The fact you can't take a listed MPG unit at face value without knowing the country of origin is the worst thing about MPG.

  • Luredreier

    Thankfully liters are smaller units then gallons, so you don't need to go all the way to 100 km to make a sensible number. In my own country we just do 10 km, or a nordic "mile" or a myriametre. So basically liters pr myriameter is our fuel economy unit of choice here.