I got an e-mail the other day from an owner-operator who was curious about why the government doesn't have to follow its own emissions rules when it comes to trucks owned by the military.

Bill Taylor and his wife are team drivers with their own truck, a 2007, paid-for Western Star with a million miles on it. They get it serviced at a Western Star dealer in Bethel, Pa.

"A few weeks ago while I was there having my truck serviced, in the next stall was a 2011 Western Star, owned by the U.S. Air Force," Bill wrote. "Looking under the hood, I noticed two things, there were no emissions [aftertreatment equipment] and the 14-liter Detroit was stamped for 'export only.' Last time I checked, Pennsylvania is part of the continental United States. A few weeks later, there was another one being serviced, surprise, no emissions and stamped for 'export only.'

"I called my Congressman Joe Courtney from Connecticut, and told one of his staff members, who I know, about this. True to form, 'We will investigate this and get back to you,' was the reply.

"We, as an industry, should be outraged at the government's failure to follow its own emission rules. We are being forced to replace trucks with engines that cost a lot more and are having quite a few problems. I can see us not sending these vehicles to Iraq or Afghanistan, last thing that I would want, is to have to pull over for a regen, while I am being shot at."

I asked Senior Editor Tom Berg, who is ex-Army and likes to keep up with the military side of trucking, what he knew about the situation. Here's what he said:

"Federal law exempts the U.S. Armed Forces' 'tactical' trucks from meeting the exhaust-emissions regulations that civilians must meet. That's why the vehicles Bill saw had 'export' Detroit engines. The soot, NOx, etc., in their exhaust gases meet 1999 regulations, but the exemption allows them to legally operate today on public roads here.

"The Department of Defense had to ask Congress for the exemption because ultra-low-sulfur-diesel fuel needed for current diesels is usually not available overseas. In Iraq and Afghanistan, the military runs everything on JP8 aircraft fuel, which is relatively high in sulfur. The trucks Bill saw might be headed there now, or must be able to go there.

"ULSD fuel is needed for proper operation of diesel particulate filters, which have been used on civilian trucks since early 2007. High-sulfur fuel like JP8, and much of the diesel fuel available outside of the U.S., Canada, Western Europe and Japan, would plug the DPFs.

"The 'Western Stars' Bill saw are from the U.S. Army's latest 'linehaul' tractor series. They use a WS cab and nose (with maybe the WS badge) on a Freightliner chassis (that's what Daimler says), and are built in Portland, Ore. Previous versions of this M-915 series are Freightliner FLD-SDs.

"The military and other government agencies do buy currently legal, civilian-style trucks and engines for non-tactical use in the U.S. (like cargo trucks and buses that work on military bases)."

I bet Bill still hasn't gotten a reply from his Congressman...