Changing Planet

Minimizing a Car’s Footprint

Several readers have pointed out the apparent contradiction of my environmental road trip in a car that burns oil, even if I did drive a hybrid. And they’re right. Over two weeks I clocked 2,200 miles and filled up five times. That’s just over 50 gallons of gasoline, or enough to fill your entire bathtub.

I wanted to find out a little about my vehicle’s impact, so I stopped at Volkswagen’s emissions test center in Oxnard, California, just south of Santa Barbara. One note of disclosure: Volkswagen is a sponsor of Change Reaction, but the decision to visit the Oxnard facility was National Geographic’s.

In tests, particulates that come out of the tailpipe are caught by a filter.

Many car makers do their emissions testing in California for a simple reason: “California has the most stringent emissions laws in the world,” Matthias Barke, the facility’s general manager, told me. If a car can pass in the golden state, then it can probably pass anywhere. That means minimizing levels of hydrocarbons and particulates that come out of your tailpipe, as well as gasses like nitrous oxide and carbon monoxide.

The process is neither simple nor cheap. In some tests engineers use fuel so pure it can cost $120 per gallon. To cover the cost of a thermal chamber to conduct climatic tests, a company has to sell thousands of cars.

As more of us turn toward hybrids or full-electric cars, we’ll obviously use less gas. A White House order from 2010 will accelerate that process, making sure any U.S. car gets 54 miles per gallon by the middle of the next decade. But as consumer attitudes continue to shift, it seemed to me that car companies will be positioned to sell lots of new cars if they can innovate their vehicles—not just to get better mileage but also to leave a progressively smaller footprint on the planet.

About the Blog

Researchers, conservationists, and others share stories, insights and ideas about Our Changing Planet, Wildlife & Wild Spaces, and The Human Journey. More than 50,000 comments have been added to 10,000 posts. Explore the list alongside to dive deeper into some of the most popular categories of the National Geographic Society’s conversation platform Voices.

Opinions are those of the blogger and/or the blogger’s organization, and not necessarily those of the National Geographic Society. Posters of blogs and comments are required to observe National Geographic’s community rules and other terms of service.

Voices director: David Braun (

Social Media