The good news is that the average fuel fuel economy of the entire US light-duty fleet improved by 40 percent over the past four decades (increasing from 13 miles per gallon to 21.6 mpg). The bad news is that Americans drive more, and with fewer passengers in each vehicle, undercutting the impact of the fuel economy gains.

That's the official conclusion of a study just released by the Sustainable Worldwide Transportation at University of Michigan Transportation Research Institute (UMTRI). Without getting too technical, the researchers found that the "occupant fuel economy" (a figure that takes mpg and vehicle occupancy into account) dropped as vehicle loads decreased by 27 percent (from 1.9 to 1.38 persons, on average) over the years. Combine the additional distance driven, up a whopping 155 percent, and that average fuel economy improvement of 40 percent drops to an occupant fuel economy gain of just 17 percent.

So what does this all mean? Saving fuel on a grand scale is more than just bumping fuel economy on the cars in the showroom. Consumers will need to drive more efficient vehicles, but they also must drive less and learn how to carpool. Easier said than done.


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  • 106 Comments
      David Hu
      • 1 Year Ago
      I don't understand some of the comments here. The increased fuel efficiency may be "undercut" by increased driving, but that also means that without it, our fuel consumption would have been much more. This survey doesn't mean the efforts to reduce fuel consumption are worthless. Some of you are jumping to the conclusion that increase fuel efficiency is alone CAUSING the higher fuel usage, but the latter could have been the consequence of increased shipment of goods, globalized economy, general trend of people moving into suburban areas surrounding cities, and the skyrocketing of real estate that's also making people willing to commute further from work. Imagine you got a $1000 bonus at work, which you then used to fix your roof. Just because you used it doesn't mean it was worthless. Otherwise, the $1000 would've come right out of your own pocket.
      venom_e92x
      • 1 Year Ago
      40 year study, give me a break. There a lot of factors that would increase this over that long of a span including the U.S. population has increased a huge amount, and lots of suburbanization has happened since then. If this study was more like a 10 year study it would be more accurate to represent current people's driving habits. Especially considering for more than nearly 30 of those 40 years fuel prices were pretty low. Pointless article.
        jnbcressy
        • 1 Year Ago
        @venom_e92x
        You are so right! My 1970 340CI Plymouth Duster used High Test Fuel (Premium). I got 16 mpg highway and alot worse around town. I also drove at about 75 mph on the highway. I had a 3.23 Posi-Grip rear axle and 4 speed standard shift. No radial tires on muscle cars back then. I remember gas wars back in the early 70\'s that I experianced in North Dakota and in Illinois. Regular was 10 cents a gallon. The fuel crisis hit in 1973 and I was in New York. Gas went from about 33 cents a gallon to 68 cents a gallon for regular. You can make any article prove your point if you don\'t factor in everything!
      citidriver
      • 1 Year Ago
      This was a 40 year study. While the fleet average has gone up (because it was mandated), there are a lot more "light truck" category vehicles out there. Every year, there are more SUVs, minivans, crossovers, larger pickups and fewer small pickups and regular station wagons in the showrooms and on the road. "Light truck" vehicles typically have a less stringent tier of efficiency and safety rules and get a break that way. This might have influenced the relatively small gains as well.
      HollywoodF1
      • 1 Year Ago
      The article seems to blame the shift in our daily driving on what we like to do. There are a lot of other sociologic and economic factors that have shifted among Americans in the last 40-years. We have increased our suburbanization and sprawl. We have expanded our highway system. And a big change has been women joining the workplace.
        BG
        • 1 Year Ago
        @HollywoodF1
        Much of that shift to suburbanization was subsidized by incredibly cheap gasoline. Gas was so cheap, we barely needed to consider how far from work the cul-de-sac was located. Maybe that is slowly changing, but for 40+ years, it was a non-issue for most suburbanites.
          GoodCheer
          • 1 Year Ago
          @BG
          Lots of other things too. Including mortgage interest deductions. In fact even having a central bank backing up mortgages permits regional banks to offer 30 year mortgages. Without cheap mortgages suburbs would have been a tough proposition.
      Cruising
      • 1 Year Ago
      I hate bar drivers such as cut off artist, tailgaters, folks that don't signal. I drive a small efficient sedan but if Jack and Jill want to drive a less efficient vehicle that's their choice just don't be a jerk on the road whatever you drive. Why get upset over what people drive you are not paying for their gas that's like judging someone over their race but not the content of their character. If you drive like a jerk piss off.
        Greg
        • 1 Year Ago
        @Cruising
        While it is your right to drive any vehicle you choose, you must admit it looks terrible whenever you see only one person in a vehicle like a Hummer H1, H2, or Lexus LX570, Toyota Land Cruiser, anything with 7-8 seats, etc. Vehicles like those without multiple passengers inside are just so off putting. Jerk drivers are the worst offense on the road though you're right.
          Cruising
          • 1 Year Ago
          @Greg
          Not as off putting as seeing a empty bus plane, or boat that requires passenger traffic for profit or a tractor trailer with no trailer because the driver is not making a profit moving goods.
          clquake
          • 1 Year Ago
          @Greg
          How do you know they didn't just drop off a bunch of other passengers? I drop off my kids @ school, drop off the neighbor & wife @ the train station, and then I have a 2 mile trip to work. Why don't you just concentrate on driving and not worry about why someone else needs to have a larger vehicle.
          S.
          • 1 Year Ago
          @Greg
          clquake, you are the exception, not the rule.
      PatrickH
      • 1 Year Ago
      Further proof that people care more about convenience than preventing global warming.
      • 1 Year Ago
      [blocked]
        GoodCheer
        • 1 Year Ago
        Why would it be unavailable? Conducting a travel survey is easy enough, lots of transportation engineering or policy groups do them.
      Sorten Borten
      • 1 Year Ago
      The increase from 13 MPG to 21.6 MPG is not 40%. It's 66%. As pointed out by others, these are two separate issues. If the fuel efficiency of the average vehicle had not increased by 66%, then that 155% increase in usage would have resulted in much higher than our current $40 Billion per month in oil trade deficit.
        mylexicon
        • 1 Year Ago
        @Sorten Borten
        The study appears to use an arithmetic mean to establish average fuel economy over the last 40 years. The calculated mean was compared to the 1970 fleet efficiency of 13mpg. Roughly speaking, we averaged about 14.5mpg in the 1970s and 20.5mpg from 1980-2010. Make a few adjustments for EPA testing changes and E10, and you end up with roughly 40%
      • 1 Year Ago
      [blocked]
      mylexicon
      • 1 Year Ago
      This is one of the laziest analyses I've ever read, and its ability to sway public opinion about the future is predicated solely on the ignorance of the common man or the willful-ignorance of the common ideologue. Thankfully the common man has the internet these days, and data is easy to come by. Fuel efficiency gains were not undone by gluttonous travel. Instead, the potential value of personal mobility was always present, and the combination of low oil prices and 40% higher fuel efficiency allowed US citizens to unlock the economic potential of personal mobility. For 25 of the last 40 years, net change in fuel economy was 0% (1980-2005) and fuel economy declined from 1986 to 2005. Our behavior was clearly not motivated by perpetually increasing fuel efficiency, but by a natural autonomous push for personal mobility to increase happiness and personal income. For 25 years we were able to leverage personal mobility to achieve prosperity and CAFE acted as a sort of economic fail-safe. Predictably, personal mobility became an economic imperative unto itself, even if the consumer's mobility was actually impeded or marginalized by low fuel economy or high MSRP. The low hanging fruit of personal mobility has been harvested, evidenced by the decline in vehicle occupancy from 1.9 to 1.38 persons. Since vehicle occupancy has a floor of 1, and baby boomer driving trends are reversing, and female participation in the workforce is stable, why would it be practical to present these trends as a means of shaping expectations about the future? The reality is that people will make the future based upon the behaviors they find to be beneficial and worthwhile. The people of 40 years ago were interested in protecting personal mobility and reducing the dollar-value of oil imports. Their behavior and policy reflected those endeavors. The people of today are interested in reducing the barrel-quantity of oil imports into the United States (oil independence) and reducing pollution via fuel efficiency and substitute fuels. Since different generations have different ambitions regarding personal mobility and fuel consumption, why is it practical to assume an identical outcome to the previous 40 years? The future will be what we decide as long as we dedicate the required resources (public and private). There is no reason to present this weak analysis to the general public as a means of swaying them towards sustainability practices beyond fuel-efficiency. Misleading information about the futility of CAFE will not help people achieve the utility they desire. I would also argue that it is more likely to encourage fatalism than investment in alternative fuels and technologies.
      Bill Burke
      • 1 Year Ago
      There goes my knee, jerking like crazy. Guess it\'s time for my \"green lobby\" buddies to call their favorite politician and demand new regulations. After I get back from hugging a few trees, I\'ll get to work on finding a way to stop people from driving their cars, visiting their relatives, and taking a vacation. Stupid Americans, never doing what we intellectuals know is best for them. This really is upsetting!
        EVSUPERHERO
        • 1 Year Ago
        @Bill Burke
        No, just stop the addiction and pull your head out of you gas. Drive EV\'s.
          Bill Burke
          • 1 Year Ago
          @EVSUPERHERO
          EV, I'm doing my part. I put only enough premium fuel in my 1970 Dodge Challenger R/T to offset the savings by my neighbor's hibrid Lexus, no more. I have no fuel robbing emission controls to hurt gas mileage, just a modified Dodge Big Block Magnum V-8 with a wicked race cam and hugh Holley 750 carb. No air conditioning, no power anything, just lots of throbbing horsepower getting an honest 9 mpg. As I said- doing my part.
          S.
          • 1 Year Ago
          @EVSUPERHERO
          Thank you for doing you're part, Bill. Long live the American V8!
      ammca66564
      • 1 Year Ago
      It's our schizophrenic policy approach here. We want people to drive less and conserve energy. But we surely don't want to raise the cost of driving, heaven forbid! So we pursue both policies at once and accomplish nothing. Gas tax, kids. That would do the trick. Phase in 5 cents a gallon a year for ten years. Won't flatten anyone financially, would be a revenue boon, would cut emissions, and people would have plenty of time to adjust. Would that really be so bad?
        IS-F Hegemony
        • 1 Year Ago
        @ammca66564
        Great another hypocritically regressive left wing tax like the cigarette tax. Who drives older less efficient vehicles? The poor. Who has to move outside the city for cheaper housing? The poor. Who have fewer options when it comes to employment and therefore have to take jobs wherever they can? The poor. How much of your 401k in green stocks? If you want to change the world put your money where your mouth is and only invest in green companies. Maybe you'll end up super rich like Al Gore. Oh is that too risky, ok then lets make everyone else pay for it via the government. No thanks.
          Ryan
          • 1 Year Ago
          @IS-F Hegemony
          The 'poor' are a scapegoat. The 'poor' aren't the ones driving the big oversized pickup trucks. The 'poor' aren't driving SUVs. They will adjust to buy more fuel efficient cars too over time.
          2 wheeled menace
          • 1 Year Ago
          @IS-F Hegemony
          No, the poor tend to drive more efficient vehicles. That's why old honda civics, corollas etc. sell for premium dollar on the used market and SUVs and largers cars depreciate like stones. It would be easier to stop subsidizing oil with wars, tax privileges, special writeoffs just for the oil industry, etc. and let the price naturally rise, rather than add a tax. It's our policy that makes gas artificially cheap. It would be strange to subsidize it, then tax it, wouldn't it?
        edward.stallings
        • 1 Year Ago
        @ammca66564
        Yes, it would be stupid. Government needs to shrink. More taxes make it grow. Government is mostly parasitic and when the parasite gets too big, the host is killed. Government functions on what it takes, backed by the power of the gun. It does not produce. It must suck off the producers. Smaller government = better government.
        oRenj9
        • 1 Year Ago
        @ammca66564
        $4/gal seems to be the magic number where people begin to actively think about conserving fuel. Since a direct federal gas tax would be a disaster, I'd suggest eliminating subsidies to gas companies as a first step. Then possibly increasing tariffs on fuel imports and gas refineries.
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