White paper

A historical review of the U.S. vehicle emission compliance program and emission recall cases

Emission recalls are a critical aspect of vehicle emission compliance and enforcement programs. An emission recall is a repair, adjustment, or modification program conducted by a manufacturer to remedy an emissions-related problem. An emission recall is quite costly to a manufacturer. A typical recall can cost millions of dollars plus reputational damage to the automakers; therefore, recalls act as a major deterrent against manufacturer emission violations. To avoid recalls, manufacturers are motivated to produce emission controls that not only pass emission certification testing, but also remain functional when vehicles are in real-world use.

Over the decades since the Clean Air Act (CAA) was initially enacted in 1963, regulators from the U.S. Environmental Protection Agency (EPA) and California Air Resources Board (CARB) have developed comprehensive and rigorous compliance and recall programs, including a number of subprograms to detect and verify emission issues. Compliance is important for achieving the public health benefits and air-quality improvements required by the standards, as well as ensuring that all manufacturers are abiding by the same rules and guidelines.

However, many emerging markets still do not have any robust emission compliance programs, even though the corresponding standards have been in place for years. In many countries, adequate legal authority is also lacking. Some markets have a partial program (i.e., a program composed of certain elements of the U.S. compliance program) but have limited resources to pursue a more comprehensive program. Most of these governments may not have adequate data sources to identify emission compliance issues.

This paper aims to provide useful information for governments that are in the early stages of pursuing an effective emission compliance program in their respective regions. This paper only focuses on toxic air pollutant emissions, otherwise known as criteria emissions, rather than greenhouse gas emissions, which is related to fuel economy. More specifically, this paper provides a comprehensive historical review of how the U.S. federal vehicle compliance program has evolved over the past 4 decades, reviews U.S. emission recall trends, highlights a few representative vehicle and engine emission recall cases and settlements, and provides insight into the data sources needed to inform a successful recall program.