I retired from Freightliner almost 4 years ago. These laws are federally mandated. It has been a nightmare for the manufacturers to comply. So much so that Catipillar finally decided it was not worth it. They got out of the on road production of heavy truck engines rather than try any longer to comply with the ever increasing emission requirements. Daimler Trucks North America owns Freightliner brand and Detroit Diesel as well as the Mercedes truck engines. They have no choice but to continue to strive for an efficient, economical, and reliable power plant that is compliant. The new engines are more expensive to produce, heavier, and less fuel efficient. Also they have to run on a low sulpher fuel that now costs more than gasoline. Isn't government regulation great?