What Is Rolling Coal?

The practice of deliberately spewing thick black smoke has the attention of authorities around the country.

A white pickup truck producing a cloud of black smokeShutterstock


If you've ever seen a diesel pickup truck spewing huge plumes of thick, black smoke from its exhaust, you've witnessed "rolling coal." It might look like a major engine malfunction, but some truck owners actually modify their vehicles to belch out enormous clouds of exhaust as a way of showing off.

Rolling Coal Is the Result of Modifications Designed to Produce More Smoke

"Rolling coal is wasting energy," said Gale Banks. "It's horsepower in the air." The California-based engineer is the founder of Banks Power, which specializes in high-performance modifications for pickup trucks and heavy-duty vehicles.

Banks earned the record for building the world’s fastest diesel-powered pickup truck, and his spinoff company, Banks Technologies, is the sole supplier of diesel engines powering the United States military's Joint Light Tactical Vehicle, which is the replacement for the iconic Humvee. So he understands how to get the most power and performance from a diesel engine.

To roll coal, Banks explained, truck owners modify their engines to take in excess fuel and insufficient air. Without enough oxygen, the fuel can't burn, spewing out as sooty black particulates.

"It's like you're making microscopic charcoal briquettes," Banks said, "and you're expelling them into my lungs."

These hard carbon particles don't all escape through the exhaust. They spread through the engine, reducing the lubricating capability of the oil and creating an abrasive that destroys pistons, turbochargers, and exhaust systems.

"There's nothing positive about rolling coal," Banks said.

Drivers Who Roll Coal Do So to Be a Nuisance

Why do some truck owners do this? Banks' disgust at the idea is plain.

"It's a social statement," Banks said. "It's, hey, look at me, I'm a bandit."

As the New York Times wrote in 2016, the toxic gesture is often aimed at "walkers, joggers, cyclists, hybrid and Asian cars, and even police officers."

"On a Sunday morning," Banks said, "[a driver rolling coal] comes up to a church lady with her window down and fills her car with smoke and laughs about it."

Tampering With an Emissions System Is Against the Law

It's a violation of federal law to defeat emissions-control devices on a vehicle registered to drive on public roads. As of 2022, however, only six states have laws expressly banning rolling coal: Colorado, Connecticut, Maine, Maryland, New Jersey, and Utah.

Enforcement is difficult because a police officer needs to witness a truck rolling coal in order to cite a driver, and most of the computer devices that enable the process can be switched on and off while driving. In recent years, the Environmental Protection Agency has begun levying fines against companies that sell emissions-defeating equipment. Banks contends that more deterrence is needed.

"These guys are making tens of millions of dollars, and the EPA is fining them, like, $500,000," he said. "There's so much money to be made with these chips, it's insane."

It's a point of pride for Banks that his record-breaking diesel hot rods don't spew out toxic clouds of black smoke. That sets him apart from some other diesel tuning shops.

"I'm hated by those guys," he said.

When Banks sees a coal-rolling pickup truck blast by, his reaction is withering.

"There's a bell-curve intelligence quotient," he said. "If you're rolling coal, you're on the wrong side of the bell curve."

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Bob Sorokanich
Bob Sorokanich is a car-obsessed journalist and editor who manages to maintain an old Mini Cooper and a love affair with automobiles while living in New York City. When he's not thinking about cars, he's riding his motorcycle, and when he's not riding his motorcycle, he's anticipating his next joy ride.