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A recent article reports that, “The auto industry beat out domestic greenhouse gas emissions standards by a “wide margin” in 2013, with cars getting an average of 1.4 more miles per gallon than required.” And that:

  1. The fleet’s mileage per gallon increased from 23.6 mpg in 2012 to 24.1 mpg in 2013.
  2. By 2025 CAFE standards dictate that vehicles get 54.5 mpg.

Bad statistics

In the first statistic, both passenger cars and light trucks (including vans, pickups, and SUVs) are included. The second statistic matches only the passenger car CAFE standard. For passenger cars in 2012 and 2013, fuel efficiency was 27 mpg and 27.3 mpg. Furthermore, this is the measured fuel efficiency. The CAFE standards for those years were 32.8 and 33.6 mpg for passenger cars.

How does the claim that “the auto industry beat standards” make any sense? It turns out that the EPA expects real conditions to be 25% worse than their testing conditions (see the footnote in this figure).

credit: epa.gov

Futhermore, automakers have other ways to meet the standards than actually decreasing tailpipe emissions. One credit is given for a car having flex-fuel capability even if the buyer only uses fossil fuel. When consumers do use high ethanol blends, they can expect lower fuel efficiency. Automakers can also get credit for over-compliance in one year and apply it to another year. These and other credits are intended to allow flexibility for companies to comply, but seems to allow automakers too much leeway.


The article also suggests that projected CAFE standards from 2012 to 2025 will save 12 billion barrels of oil, $8000 for each driver, and prevent 6 billion tonnes of GHG emissions. However, there is no context.

The US uses 7 billion barrels of oil each year. That means the standards will save us 1.7 years of oil consumption. This seems pretty good, but remember that these calculations are already taking into account the expansion of hybrid and electric vehicles.

$8,000 for each driver is an estimate. It’s based on the oil saved, but the price of oil can change. Not only that, but the CAFE standards will indirectly change the price of vehicles. And if it is ultimately cheaper to drive, more people will be able to afford to drive (if not in the US, car ownership seems likely to increase in other countries).

US emissions are about 6 billion tons of GHGs each year, so the standards will save us a year’s worth of emissions. Not bad, but again not nearly enough since transportation in the US over that time period will still amount to nearly 16 billion tons of emissions.

Real solutions

These solutions are less likely to become public policy, but more necessary to reduce emissions.

There is huge potential in carpooling. Since the actual goal (energy-wise) of a vehicle is to transport people, having two people in your car for every trip essentially doubles your real fuel efficiency.

Car sharing also has the potential to reduce costs. Since fewer cars are needed, manufacturer footprints will decrease. Combined with carpooling could provide a more flexible option to public transportation.

Public transportation itself is useful, but truly effective only if an area is densely populated. Luckily, many of the world’s people are migrating to cities. This will allow walking, biking, and public transport to displace private vehicles.

Driving, especially in the US, ultimately has to be made more expensive. Low-income assistance might be necessary, but there is huge potential in reduction of emissions. As fuel or car fees become more expensive over time, people will adopt the solutions above that best fit their situation and lead us to more sustainable lifestyles.