I remember the first time someone rolled coal on me. It was 2006, and I was driving to work at the University of Kentucky. It was a bright, sunny day in Lexington, and I had the roof down and was stopped in traffic behind a large pickup truck with decidedly non-standard exhaust pipes exiting straight up behind the cab. Whoever was driving the pickup evidently noticed the Miata in his mirror and enveloped me in a thick cloud of soot when the lights changed.
As automotive subcultures go, intentionally modifying your truck’s diesel engine to make extra pollution is one of the more antisocial ones out there. According to the US Environmental Protection Agency, diesel trucks with disabled emissions controls are far more widespread than you might think and emit more pollution than the diesel engines that got Volkswagen such hefty fines.
In 2016, Volkswagen agreed to a pair of court settlements totaling nearly $16 billion after it was caught selling diesel vehicles fitted with emissions defeat devices. In total, the VW scandal affected more than half a million cars and SUVs sold in the US, which produced up to 40 times the legal limit of nitrogen oxides (NOx) when in daily operation.
According to the EPA’s Air Enforcement Division, the use of aftermarket emissions defeat devices by diesel truck owners rivals that problem. In a report first obtained by The New York Times, it estimates that 550,000 medium trucks have had their emissions systems tampered with over the last decade—fully 15 percent of the diesel trucks on US roads.
In fact, the EPA analysis is limited to class 2b and class 3 diesel pickups—trucks with gross vehicle weights between 8,501 to 14,000lbs (3,856 to 6.350kg)—based on data obtained from the agency’s civil enforcement investigations involving tampering that happened between 2009 and 2020. And specifically, the EPA says it’s only counting tampering where all of a truck’s emissions controls are removed, as opposed to mods that leave “emissions controls hardware intact and operational.”
They sure are dirty. The EPA report says that 570,000 tons of excess NOx and 5,000 tons of excess diesel particulates are the result over the course of these trucks’ lifetimes. Or to put it another way, “due to their severe excess NOx emissions, these trucks have an air quality impact equivalent to adding more than 9 million additional (compliant, non-tampered) diesel pickup trucks to our roads.”
And that’s bad, because it’s abundantly clear that higher levels of these airborne pollutants kill people.
As you might expect, the practice of removing emissions controls from one’s truck is a more prevalent practice in states without regular vehicle inspections. North Dakota leads the way with an estimated 18.6 percent of diesel trucks having been tampered with; by contrast the agency estimates the incidence of tampering in California to be 1.8 percent.
However, North Dakota is a sparsely populated state. And while estimated rates of diesel truck tampering are lower elsewhere, Texas leads the way numerically with nearly 65,000 tampered trucks, according to the study.