Increasing Fuel Efficiency Is Good, But It's Not Everything

Legislation passed by Congress to raise fuel effiency is a welcome first step. Photo by Storm Crypt.

As an engineer working in the field of sustainable transport I am very excited about the latest efforts to improve fuel efficiency, which will certainly help in the fight against climate change, a global phenomenon dating back to the start of the industrial revolution. (As an aside, the New York Times has a really neat graphic on this). One has to praise the US Congress for moving ahead legislation which will boost automobile and SUV fuel efficiency for the first time since 1975.

Nevertheless, as we have been claiming on this blog, this effort will not be enough! We have to do more. Lee Schipper, a colleague of mine and a fellow contributor to TheCityFix, says it well: “We also need to drive smaller, lighter vehicles. And we need to drive them less.”

The reason why he’s right has to do with an algebraic formula that’s really quite simple:


Using this equation, we can see that by improving fuel efficiency, we’re only effecting one of several variables related to total carbon emissions. But if people continue to buy more polluting cars, regardless of whether they are fuel efficient, and drive them longer distances, any gains in fuel efficiency might not do all that much.

The way the transport sector can fight climate change is by adopting a holistic approach that focuses on all three variables: total car travel, fuel efficiency, and carbon emissions per gallon of fuel. Here’s how we can do it:

  • Reducing total car travel by promoting zero-emissions modes like walking and biking. Of course you can’t expect people to walk to work who live 50 miles from their office; after all, in the United States car commuters spend around 100 minutes on average getting to work and back. In many cases this is totally unnecessary because advances in telecommunications make telecommuting easier than ever. What’s more sprawling suburbs and satellite exurbs where walking is impossible are vestiges of the past. The urgency of global warming and energy insecurity demands that cities regulate the way that land is used, making mixed-use, high-density neighborhoods a priority.
  • Reducing total car travel by improving public transportation. Currently, only 4.7% of people get to work using public transportation whereas 87.8% of people go by automobile. What this means is that buses, streetcars, and subways must be attractive alternatives to get people out of their cars. So they must come often, cover a large portion of the city, have seamless integration with other transit infrastructure like airports, and be comfortable and cost effective.
  • Increasing fuel efficiency through technology improvements mandated by legislation.
  • Increasing emissions standards through technology.

Even when considering all the various ways for reducing carbon emissions, raising the fuel efficiency standards, a move that was accepted by the auto industry, should still be considered a good step, especially considering the recent political environment. But with that said, we still need more!

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