There have been two approaches to regulatory compliance: EGR and SCR. EGR was implemented January 1, 2007 and SCR was implemented January 1, 2010. EGR was able to meet the Federal Standards for 2007, but not able to meet the new standards for 2010.

In 2007 the Emissions Standard was 1.2 NOx (g/hp.pr) and it could be reached using EGR technology, but January 1, 2010 this standard dropped to .02g/HP-hr NOx and .01 g/HP-hr particulate matter. EGR technology could not meet this standard for large diesel engines. Several tried to enhance EGR, but fell short of reaching the new standard. SCR became the technology for all new vehicle production.

EGR and SCR are the primary strategies implemented to this point. EGR addresses emissions within the combustion chamber by lowering exhaust gas temperatures while SCR addresses emission reduction through the use of a catalyst and a diesel exhaust fluid (DEF) to lower NOx.