Working Paper

In-use Testing for CO2 and Fuel Economy in the United States


China is considering including an after-production conformity test as part of China’s Phase 3 passenger car fuel consumption standard implementation and enforcement plan and is looking for experiences from the existing practices in the US for the light-duty vehicle CAFE and GHG emissions standards compliance. The purpose of this short paper is to provide an overview of the US in-use vehicle COemissions regulation, relevant in-use emissions compliance tests, and to focus on key questions including: 1) What are the criteria for selecting vehicles for the in-use test? 2) What is the ratio (or is there a required ratio) between the number of in-use vehicles selected and the number of vehicles in the test group at the certification? 3) How does EPA perform the tests? 4) How does EPA determine whether an in-use vehicle is in compliance? 5) Is there an allowable error margin (or deterioration level) between the in-use COtest result value and the value at certification? 6) What are the detailed procedures of recruiting vehicles from consumers? 

The structure of this paper is as follows: i.) a brief introduction of the US in-use program in the broad context of the overall EPA compliance framework, ii.) a description of the new in-use COemissions compliance requirement under the US 2012-2016 Model Year Light-duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards, iii.) an explanation of the in-use compliance tests performed by manufacturers and by EPA, iv.) a discussion of the additional test burden for the new in-use COcompliance rule compared to testing for in-use criteria pollutants only, v.) a focus on the penalty for not complying with the in-use COrequirement and vi.) useful experiences for China to consider.