Control of greenhouse gases from motor vehicles

The transportation sector is one of the greatest contributors of greenhouse gas (GHG) emissions. This sector accounted for 27 percent of total GHG emissions in 2020. Within the sector, light-duty vehicles make up 57 percent of these emissions, followed by medium-and heavy-duty trucks at 26 percent. A typical passenger vehicle emits roughly 4.6 metric tons of carbon dioxide per year. In comparison, a vehicle that operates only on electricity will not emit any tailpipe emissions, although electric vehicles contribute to greenhouse gas emissions from the electricity produced to charge them.

There are various regulations for greenhouse gases of different transportation types. Many regulations are becoming increasingly strict to reduce transportation-related air pollution. This matches President Biden’s pointed direction of massive greenhouse-gas reductions. He aims to achieve net-zero emissions by 2050 within the federal government and 100 percent zero-emission vehicle acquisition by 2035.

In December 2021, the Environmental Protection Agency (EPA) finalized revised national GHG emissions standards for passenger cars and light trucks for Model Years 2023-2026 (40 CFR 86 and 600). Following this, EPA released a final rule on the control of greenhouse gases from new heavy-duty engines and vehicles. The rulemaking changes relate to test procedures, regulatory useful life, emission-related warranty, and other requirements. It goes into effect on March 27, 2023. This action likely affects companies that manufacture, sell, or import into the United States new heavy-duty highway engines.

The final rule should cause a 48 percent reduction in highway heavy-duty emissions of nitrous oxide. It will also impact vehicle sales due to changes in purchase price and longer emission warranty mileage requirements. Both vehicle emissions rules are far stricter than previous standards. This trend will likely continue for many years to come.

Gases that trap heat in the atmosphere are called greenhouse gases. They include carbon dioxide, methane, nitrous oxide, and fluorinated gases. Each of these stay in the atmosphere for various amount of time. Some linger for a few years and others for thousands. They warm the planet and impact precipitation and sea levels.