Hi Lazboytt,
Some HMMWVs have GM engines with labels that say they comply with EPA standards for the year of manufacture, so if someone were to make a statement that HMMWVs "are not street legal due to not being manufactured to US E.P.A. emissions standards", that is not true for all HMMWVs.
Here is a picture of the label on a GEP 6.5 engine, which was built under a National Security Exemption. It lists the relevant sections of the law for the NSE:
40 CFR 85-1708 says: A manufacturer requesting a national security exemption must state the purpose for which the exemption is required and the request must be endorsed by an agency of the Federal Government charged with responsibility for national defense.
Clean Air Act Section 203 (b)(1) corresponds to US Code Title 42 Chapter 85 Section 7522(b)(1), which says: The Administrator may exempt any new motor vehicle or motor vehicle engine, from subsection (a) of this section, upon such terms and conditions as he may find necessary for the purpose of research, investigations, studies, demonstrations, or training, or for reasons of national security.
Regarding the applicability of the exemption over the life of the vehicle, this became an issue in 2014 when the DLA stopped releasing vehicles to law enforcement and fire departments, and selling them to the public, over concerns about the emissions legality of the arrangement. The issue was settled when the EPA agreed that the exemption would continue even after the national security mission was concluded. This decision was posted on the DLA website. Here is a screenshot:
The EPA is required to keep a list, and make it available to the public, of all non-road and marine engines that are granted a NSE. (See 40 CFR 91.1008 and 89.908 ). I am not aware of any requirement that the EPA keep a list of on-road engines that are granted a NSE, but they may have it. But the NSE label should be taken at face value for any particular engine, same as a regular emissions label that states compliance with the regs...
