The Environmental Protection Agency maintains a listing of “off-cycle” vehicle technologies that reduce emissions but are not sufficiently accounted for in city and highway test cycles. These technologies include active aerodynamics, thermal control technologies, active warm up, engine idle stop-start, high efficiency lighting and alternators.
Manufacturers can gain credit toward meeting their emissions requirements by adopting these technologies and several saw widespread adoption by vehicle manufacturers for the 2020 model year. The use of thermal glass or glazing to reduce transmission of heat from the sun reached a production share of 89%, followed by high efficiency lighting at 85% and passive cabin venting at 78%. All of the technologies shown reached a production share of 13% or greater for the 2020 model year.
Source: U.S. Environmental Protection Agency, 2021 EPA Automotive Trends Report, EPA-420-R-21-023, November 2021.