Gallery: MIT Researcher Explains Why Gas Mileage is Still Low Despite A...


If you live in the United States and value fuel efficiency, you might catch yourself looking longingly overseas at super efficient vehicle fleets and wondering, why not us? One MIT researcher looked into the predicament and found that though it might not look like we are making strides, we are. The average, fuel efficiency for US vehicles actually increased by 60 percent between 1980 and 2006. The problem is that cars in the US got bigger (by 26% on average) and their horsepower increased (by 107 hp on average), which, when factored in, means that the average fuel efficiency of American cars only increased by a mere 15%. Almost all of the new technology went into making cars more efficient per pound of weight so that the cars could get bigger and still fit within average mile per gallon expectations.

I find little fault with the auto manufacturers, because there has been no incentive to put technologies into overall fuel economy,” said MIT economist Christopher Knittel, author of the study. “Firms are going to give consumers what they want, and if gas prices are low, consumers are going to want big, fast cars.” Knittel found that when adjusted for inflation, the price of gas dropped 30% between 1980 and 2004.

Knittel used numbers from the National Highway Traffic Safety Administration, auto makers and trade journals to compile his research. He found that in 1980 light trucks were just 20% of the US vehicle fleet. In 2004 light trucks — with the addition of SUVs — made up 51% of the fleet. Knittel punctuated his paper with a strong opinion that in order to use those advances in fuel efficiency to decrease gas use and emissions we’ll need the government to step in and do some friendly nudging. “When it comes to climate change, leaving the market alone isn’t going to lead to the efficient outcome,” Knittel says. “The right starting point is a gas tax.”



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  1. Brian Petroski September 7, 2014 at 1:46 pm

    What about the carburetor that were invented twenty years ago that provided 100 miles per gallon before the technology was bought and shelved?

  2. amandanic August 1, 2012 at 1:34 pm

    A tax on gas? Yeah let’s go all communist and keep Americans from driving because there is a tax on gas. First of all, taxes are already included in the price per gallon. Second of all, Americans need to be given more options of affordable cars that do the climate good rather than pollute more.

  3. sammael February 2, 2012 at 10:38 am

    I don’t know if you are aware but both European and Asian cars have far MORE safety features, heavier safety glass, stronger brakes, etc, in their domestic markets. To the point that you can’t use same model Mercedes american parts in european car. Yet they are more fuel efficient AND safer.
    They also cost A LOT more.
    What I am saying is:
    You can have
    1: Cheap (or atleast affordable)
    2: Fuel efficient
    3: Safe

    Pick two.

  4. drm January 27, 2012 at 5:07 pm

    Over in Europe .The frankfurt auto shows . They are building mid-size gas powered dual turbocharged cars that get as good of mileage as the Prius Hybrid and have the same Carbon footprint !!. No batteries to change and find places to dispose of them or have to change.Even less weight.How about an 800 HP dual turbo 350 in a 56 chevy that passes smog.Oh Yes it does

  5. Greendogo January 23, 2012 at 3:24 am

    We need to get rid of all the pretense that the government can or should guide automakers to make specific kinds of cars. We should also extinguish the speed limits. As a libertarian, when I see a government restriction on speed I habitually want to break it. But upon reflection, if there were no speed limits, I think I would factor in increased drag and fuel economy.

    tl;dr – I feel like speed limits are now thought of as mostly speed targets by the average driver.

  6. jhertel January 22, 2012 at 5:03 pm

    Thanks, Robert Anderson, for mentioning the speed limits! Many people are too nearsighted (and unknowledgeable) to think that far.

  7. johnny5 January 9, 2012 at 10:03 am

    I’m with Blogger37. The leading cause of lower gas mileage is because we put ethanol in our tanks. We do NOT need more government regulation. People should be allowed to demand what they want, and suppliers should be allowed to supply what the demanders want. It’s called FREE TRADE and CAPITALISM. …I miss freedom…

  8. zeppflyer January 7, 2012 at 3:47 pm

    While increasing the gas tax and indexing it to inflation is part of the solution, we could also stand to build our cars like the rest of the world. That is; fewer weighty, power-guzzling, aerodynamics-destroying, government-mandated ‘safety features’. Overbuilt passenger compartments, giant crumple zones, airbags everywhere, and the blunted front ends mandated by pedestrian safety laws take a big bite out of the efficiency of our cars and prevent some of the more efficient models seen in the rest of the world from coming here.

    Another cue that we could take would be the adoption of European traffic patterns, specifically the greater use of roundabouts rather than stoplights and yields rather than stop signs. Slowing down a bit to ascertain that an intersection is clear and then breezing through, all the while conserving momentum, is far more economy-friendly than coming to a complete stop and quickly accelerating again. It also causes less wear and tear on the car, necessitating fewer replacement brake shoes, transmission rebuilds, and new cars. Furthermore, this change would reduce demand for the powerful engines and low-geared transmissions needed to constantly bring a car up to speed from a complete rest.

  9. trustme January 6, 2012 at 6:47 am

    The right starting point is a tax on big, fast cars…

  10. Blogger37 January 5, 2012 at 10:50 pm

    Why no mention of lowed gas mileage due to mandated use of ethanol in auto fuel?

  11. Robert Anderson January 5, 2012 at 4:20 pm

    One major reason fuel economy is low is simple: GOVERNMENTS DO NOT ENFORCE THE SPEED LIMIT, and therefore PEOPLE DRIVE AS FAST AS THEY LIKE.

    C’mon, people, this is relatively simple physics. Travel energy expended (because of aerodynamic drag) increases roughly with the SQUARE of the velocity.

    Try this experiment: On ANY multi-lane road, drive in the right or center lane at the speed limit. Scrupulously. You will be passed with impunity. You will also probably catch up with most of the people passing you at the next traffic control (unless you’re on an expressway.)

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