An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Verified Technologies for SmartWay and Clean Diesel

Aerodynamic Wind Tunnel Testing for SmartWay Verification

This document describes:

  • What a wind tunnel test is;
  • What kind of measurements are used in wind tunnel testing;
  • How wind tunnel test results relate to the real-world; and
  • How wind tunnel test results compares to results achieved using other test methods.
You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.