Cars do not typically release significant amounts of methane; their primary emission is carbon dioxide from burning fossil fuels. However, vehicles running on natural gas, such as compressed natural gas (CNG) or liquefied natural gas (LNG), can emit methane due to incomplete combustion or system leaks, known as "methane slip."
Most conventional cars with internal combustion engines use gasoline or diesel, which produce carbon dioxide (CO2) as the main greenhouse gas, along with pollutants like nitrogen oxides (NOx). Methane (CH4) is a potent greenhouse gas with a global warming potential about 25 times greater than CO2 over 100 years, but it is not a standard emission from these engines. Instead, methane is more commonly associated with sources like agriculture or natural gas production.
For natural gas vehicles, methane emissions can occur during refueling, from the fuel storage system, or if combustion is inefficient. According to industry standards set by organizations like the Environmental Protection Agency (EPA), while CNG vehicles offer lower CO2 emissions compared to gasoline, they require careful maintenance to minimize methane leaks. Properly tuned engines and regular checks can reduce these emissions significantly.
To illustrate, here is a comparison of average methane emissions for different vehicle types based on authoritative data:
| Vehicle Type | Fuel | Methane Emissions (grams per mile) | Key Notes |
|---|
| Gasoline Car | Gasoline | 0.02 | Negligible, primary concern is CO2 |
| Diesel Car | Diesel | 0.01 | Very low emissions |
| CNG Vehicle | Compressed Natural Gas | 0.6 | Higher due to fuel composition and potential leaks |
| Hybrid Electric | Gasoline/Electric | 0.02 | Similar to conventional gasoline |
| Electric Vehicle | Electricity | 0 | No tailpipe emissions |
| LNG Truck | Liquefied Natural Gas | 0.8 | Common in commercial vehicles, requires monitoring |
This table highlights that methane release is primarily a consideration for alternative fuel vehicles. For car buyers concerned about environmental impact, opting for electric vehicles or ensuring CNG systems are well-maintained can help. Regular maintenance, such as inspecting fuel lines and using certified technicians, is essential for minimizing emissions.
