Search Carbonrally

Challenge Activity

These people have all recently accepted this challenge.

01/13/09 AKWells accepted this challenge, reducing CO₂ by 30 lbs so far.

01/13/09 Karens accepted this challenge, reducing CO₂ by 30 lbs so far.

01/13/09 jfein82 accepted this challenge, reducing CO₂ by 30 lbs so far.

01/13/09 Ice accepted this challenge, reducing CO₂ by 30 lbs so far.

01/13/09 infotrender accepted this challenge, reducing CO₂ by 30 lbs so far.

Leave Your Car At Home Featured on Oct 15, 2007

Alternative content

Challenge Details

Note to our veteran Rallyers: We’ve decided to “tune up” our commuting Challenges for 2009. Since the launch of Carbonrally, we’ve found that folks lose focus when a Challenge is too general. “Leave Your Car At Home” is very general. So, we’ve taken down this Challenge and are making the commuting Challenges more specific. We hope this makes the actions more concrete and specific for you. We also hope this will better focus the conversation and give folks a chance to share insights about specific green ways to travel. Stay tuned for additional commuting Challenges, which will include such carbon savers as carpooling , telecommuting, biking to work, and so on.


Commuting by car is part of “the daily grind” that doesn’t have to be so much of a grind. You already do what you can to keep your traffic stress down. You’ve got your decaf and your MP3 player. You even try to smile at another driver now and then. Want something even less stressful? Park your car one day this week, strap on a backpack, and walk to school or bike to work. Or, carpool with a friend. Same ground, less grind.

The Carbon Connection
The more we drive, the greater our carbon impact. Close to 30% of the greenhouse gases released in the United States come from transportation. Of that amount, over 80% is produced by our vehicles driving on the roads (cars, trucks, buses) and burning gasoline or diesel.

In the 1990s, greenhouse gas emissions from American automobiles increased almost 20%. And that trend continues in this decade. Car ownership is up; vehicle occupancy is down. Carpooling and the number of people who walk instead of driving has dropped by half since 1980. People are making more trips in their cars and commuting farther. And unfortunately the average fuel efficiency of passenger cars, including small trucks and SUVs, has actually decreased over the last 20 years.

Here’s the scary part. Each gallon of gasoline burned in an average car’s engine blows 19.4 pounds of CO2 out the exhaust and directly into Earth’s atmosphere. Just think. With a gas tank size of 15 to 18 gallons, that’s an incredible 350 pounds of CO2 you’re releasing each time you’ve driven around town enough for your fuel gauge to hit Empty.

Getting It Done
Need help meeting this Challenge? Here are a few simple suggestions:

• If you live close enough to your school or work to walk, do that. If it’s a little farther away, maybe you can ride your bike.
• Use public transportation — trains, buses, etc. — if it’s available.
• See if you can carpool with someone one day this week. Maybe you can even carpool with a fellow Rallyer. (Hint: To find Rallyers in your town or city, click on your user name at the top right of any page. That will take you to your My Carbon Page. Then click on the name of your town. On the town page, you can see other Rallyers who live in your town or leave a comment where you can look for carpool buddies.)
• Telecommute one day this week, if you can.

Do you have other suggestions? Share them in the comments section below.

Rules of the Challenge
This Challenge invites you to start small and think big. When you leave your car at home just one day this week, you and your team will be credited with 30 pounds of CO2 savings. Imagine how that will all add up as Rallyers across the country join together to take this same Challenge and reduce their carbon impact. Remember, this is a repeatable Challenge. So, come back later, take this Challenge again, and save another 30 pounds of CO2!

Learn More
Union of Concerned Scientists: Clean Vehicles
How Can a Gallon of Gasoline Produce 20 Pounds of Carbon Dioxide?

See the Math
Let’s start with the known or estimated numbers:

• Assume an average daily commute of 16 miles each way to school or work. That’s 32 miles driven each day for just commuting.
• The average car used in commuting to work or school gets 21 miles per gallon of gasoline.
• Each gallon of gasoline burned by an automobile engine leads to the release of 19.4 pounds of CO2 into the atmosphere.

Now put all that together to get the following equation:



Your numbers may vary. Your total daily commute may be longer or shorter than 32 miles. Your car may get better or worse mileage. However, the important thing to look at here is just how much carbon dioxide gets formed and released each day as you drive your car. At almost 20 pounds of CO2 for every gallon of gas you use, cutting back on any driving you do can make a huge carbon impact.

Discussion 74 comments so far