The average passenger car in the U.S. produces about 4.6 metric tons of carbon dioxide (CO2) per year. This figure is based on burning approximately 550 gallons of gasoline. However, the actual amount varies significantly based on the vehicle's fuel efficiency, annual mileage, and driving habits. Fundamentally, for every gallon of gasoline burned, a car releases about 8,887 grams of CO2 into the atmosphere.
This calculation comes from the Environmental Protection Agency (EPA), which states that the average vehicle driven 11,500 miles per year at 22.0 miles per gallon (mpg) will emit this amount. The core of the issue is basic chemistry: when gasoline (primarily composed of hydrocarbons) burns, it combines with oxygen to produce CO2 and water vapor.
The following table provides emissions estimates for a range of vehicles based on different fuel economies, assuming an annual driving distance of 11,500 miles. This illustrates how much of a difference your car's efficiency makes.
| Vehicle Fuel Economy (MPG) | Annual CO2 Emissions (Metric Tons) | Gasoline Consumed (Gallons/Year) |
|---|
| 15 mpg (Large SUV/Truck) | 6.8 | 767 |
| 22 mpg (U.S. Fleet Average) | 4.6 | 523 |
| 35 mpg (Modern Compact Sedan) | 2.9 | 329 |
| 50 mpg (Hybrid Vehicle) | 2.0 | 230 |
| 100 mpg (Plug-in Hybrid EV) | 1.0 | 115 |
| All-Electric Vehicle (EV) | 0* | 0 |
Note: While EVs produce zero tailpipe emissions, the electricity used to charge them generates CO2 at the power plant. The national average for an EV is equivalent to about 2.0 metric tons of CO2 per year, or a gasoline car that gets 82 mpg.
Beyond the car itself, your driving style has a major impact. Aggressive acceleration and high-speed driving can lower your fuel economy by 15-30%, directly increasing CO2 output. Properly inflated tires and regular maintenance (like clean air filters) are also critical for ensuring your car operates at its optimal efficiency, minimizing unnecessary emissions.
