They call it “rolling coal.” But only because “being a total jackass” was already taken.

I was on Interstate 15 a few weeks ago, driving home from work, when I witnessed what was either a childish example of road rage or a miniature act of eco-terrorism. Possibly both.

A large diesel pickup truck was a few vehicles ahead of me, driving in the middle lane behind a car that was apparently not going fast enough for the truck driver’s tastes. Suddenly, the truck swerved into the fast lane and accelerated, leaving a cloud of black smoke.

Once the truck driver had successfully passed, he or she pulled back into the middle lane and slowed for a moment, allowing the offending car to catch up. Whereupon our hero hit the accelerator again, leaving an even larger cloud of thick, black exhaust for the poor, poky driver — and those of us unlucky enough to be in the vicinity — to muddle through.

“Rolling coal” is defined as intentionally disabling the computerized emission controls on a diesel engine so that the vehicle emits a dark, sooty exhaust. Car-guy friends tell me the modification basically dumps more fuel into the engine, and that the black smoke comes from poorly burned diesel fuel.

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The initial idea behind rolling coal was to improve power to the engine, and as those in the know point out, even a well-tuned diesel engine will smoke when it’s placed under a load. But pretty soon, guys with diesel pickups realized they could emit a cool plume of black exhaust by tampering with the pollution controls on their vehicles. One blogger calls it “pollution porn for dudes with pickup trucks.”

And then, about a year ago, rolling coal became a way to protest the environmental movement — possibly because driving all the way to the nearest zoo to club baby seals seemed like way too much trouble. Rather, striking a blow against the liberal greenies was as close as your accelerator pedal. And indeed, some rolling-coal lovers, referencing a certain small Toyota hybrid vehicle, call the inky black discharge “Prius repellent.”

There’s a local component to this rolling-coal story. In January 2013, the Ogden-based automotive electronics manufacturer Edge Products LLC reached a settlement with the Environmental Protection Agency. Edge agreed to pay a $500,000 civil penalty, among other remedies, after manufacturing and selling more than 9,000 electronic devices that effectively allowed vehicle owners to create a trail of dark, black smoke by bypassing their “diesel particulate filters.” The EPA estimated that the illegal devices sold by Edge would result in 158 tons of excess particulate-matter emissions.

“This is equivalent to the emissions from 422 new long-haul semi trucks operating for a period of 29 years,” the EPA said in a press release. And considering all the talk in recent years about Utah’s poor air quality, that seems significant.

Rolling coal isn’t going anywhere anytime soon; typing “diesel performance chips” into Amazon.com returns almost 76,000 hits. Which makes one wonder what’s displayed in the website’s helpful “Customers who bought this item also bought …” feature. My guess:

• Male enhancement products 

• White ribbed tank top undershirts

• Confederate flags

• Donald Trump 2016 bumper stickers

• Matching wedding rings for first cousins

• Toothpaste and deodorant

OK, so I was just kidding on that last one.

Still, to see all these rolling-coal videos online — featuring yay-hoos smoking out pedestrians, bicyclists and other motorists — it’s difficult not to think there’s something seriously wrong with these folks.

I was talking with my self-described “gearhead” neighbor the other day, and while he admits he loves a good muscle-car burnout, he just doesn’t get the attraction of rolling coal. In fact, he can’t help but wonder if perhaps some of these diesel truck owners aren’t just “compensating.”

Compensating?

“I am not saying that you have small genitalia,” he explains. “Your truck already did.”

Contact Mark Saal at 801-625-4272, or msaal@standard.net. Follow him on Twitter at @Saalman. Like him on Facebook at facebook.com/SEMarkSaal.