Rolling coal

In 2021, six bicyclists training for a road race were run over by a 16-year-old who was rolling coal along Business U.S. Highway 290 in Waller County, Texas, outside Houston, when he attempted to drive ahead of the group to engulf them in the exhaust.

[14] In July 2014, the United States Environmental Protection Agency stated that the practice was illegal, as it violated the Clean Air Act which prohibits the manufacturing, sale, and installation "of a part for a motor vehicle that bypasses, defeats, or renders inoperative any emission control device" and "prohibits anyone from tampering with an emission control device on a motor vehicle by removing it or making it inoperable prior to or after the sale or delivery to the buyer.

... "Businesses that manufacture and sell illegal devices to defeat a vehicle's emissions controls foster pollution and risk decades of progress in curtailing harmful emissions from motor vehicles in this country," said Assistant Attorney General Todd Kim of the Justice Department's Environment and Natural Resources Division.

[18]In 2023, companies in Idaho and California pleaded guilty in federal court to conspiracy to violate the Clean Air Act and agreed to fines of US$1 million each.

[18] California law prohibits operating a vehicle "in a manner resulting in the escape of excessive smoke, flame, gas, oil, or fuel residue.

[51] In 2016, a question to the Western North Carolina Air Quality Director about "rolling coal" referenced state law.

"[53] During any mode of operation, diesel-powered vehicles cannot emit for longer than five consecutive seconds visible contaminants darker than a specific density.

[55] Reports on smoking vehicles can still be made through the North Central Texas Regional Smoking Vehicle Program in the Dallas–Fort Worth area, which includes Collin, Dallas, Denton, Ellis, Erath, Hood, Hunt, Johnson, Kaufman, Navarro, Palo Pinto, Parker, Rockwall, Somervell, Tarrant, and Wise counties.

[59] In March 2020, cast members of the Utah-based Diesel Brothers reality television series, and the companies they own, were fined a total of US$850,000 for Clean Air Act violations.

[66] A first attempt in July 2016 failed,[66] but Cheyenne police had clarified at that time that they had been writing tickets for coal rolling under state law.