A group of diesel truck enthusiasts in British Columbia insists their only goal is “higher horsepower,” despite sharing a name with American motorists whose primary aim appears to be flouting environmental regulations.

Coal rolling groups are popping up across the country. “Rolling coal” refers to the practice where diesel truck owners rev their engines to full power in order to spew thick, black smoke from their exhausts. Many truck owners who like to roll coal have modified their vehicles to maximize the effects, and even installed smoke switches so they can do it on demand.

But a growing number of videos posted to YouTube and Tumblr showing coal rollers blowing the smoke at passing Prius drivers and cyclists is giving the practice a bad rep.

One of the administrators of the B.C. Coal Rollers Club insists their group is “just a diesel enthusiast club” that doesn’t deserve to be lumped in with the American coal rollers whose online videos have attracted attention of U.S. lawmakers.

"I joined because I know if my truck breaks down on the side of the highway there's going to be a team of guys that are going to show up and help,” Josh McDonald told CTV Vancouver.

The group’s members drive trucks souped up with thousands of dollars worth of modifications. Similar clubs are springing up across the country, where members meet to talk trucks and show off their rides.

But the antics of coal rollers south of the border seemed to be aimed at flouting environmental laws, McDonald says.

“They seem to be doing it as more of a protest,” McDonald says of the behaviour. “It's an intentional middle finger to the environmentalists and the EPA.”

Indeed, the EPA (the U.S. Environmental Protection Agency) says “rolling coal” is illegal because it contravenes the Clean Air Act. The legislation prohibits tampering with or removing emission control devices from vehicles after they’ve been driven off the dealer’s lot.

The growing number of online videos showing coal rollers attacking cyclists and others spurred the EPA to issue a reminder notice about the Clean Air Act’s provisions.

In 2012, a panel working on behalf of the World Health Organization classified diesel engine exhaust as carcinogenic to humans. Research shows that exposure is linked to a higher risk of lung cancer, the panel concluded.

McDonald admits that some prospective new members want to join in order to flout environmental regulations and it can be a challenge to keep some members focused on simply showing off their trucks.

But he makes it “very clear to them very quickly” that “we don’t support that kind of behaviour.”

"We're not trying to protest anything and we don't think it's cool to pollute the environment or smoke people out at intersections or anything like that,” McDonald said.

Member Kent Clemas says the group is “about achieving higher horsepower, seeing how much power we can put to the ground.”

Another member, Devon White, says he only intentionally “rolls coal” if he’s on a track. A truck would naturally spew a lot of smoke if the engine is under a heavy load or towing up a hill, he said.

The group will not change its name despite the negative associations with others south of the border, McDonald says. And with Vancouver’s vehicle emissions testing program, AirCare, being phased out by the end of the year, coal rollers will likely only face a small fine.

With a report from CTV Vancouver’s Penny Daflos