EPA oversees a broad set of compliance activities to ensure that vehicle and engine manufacturers satisfy their regulatory obligations. These activities include issuing certificates of conformity before vehicles and engines enter commerce, monitoring and testing vehicles and engines that have been sold and are “in-use,” auditing manufacturers and their testing facilities, and monitoring required reporting.

EPA periodically issues progress reports on vehicle and engine compliance activities. The latest report covering the 2014-2017 model years was issued in April of 2019 and updates and builds upon the data and information presented in the first four reports, which cover compliance activities for the 2007 – 2013 model years.

• 2014-2017 Progress Report: Vehicle Engine & Compliance Activities (PDF) (122 pp, 8.08 MB, EPA-420-R-19-003, April 2019)
• 2012-2013 Progress Report: Vehicle Engine & Compliance Activities (PDF) (87 pp, 2.2 MB, EPA-420-R-15-007, October 2015)
• 2009-2011 Progress Report: Vehicle and Engine Compliance Activities (PDF) (74 pp, 11 MB, EPA-420-R-13-006, December 2013)
• 2008 Progress Report: Vehicle and Engine Compliance Activities (PDF) (49 pp, 3.9 MB, EPA-420-R-10-022, August 2010)
• 2007 Progress Report: Vehicle and Engine Compliance Activities (PDF) (64 pp, 890 K, EPA420-R-08-011, October 2008)