Truck drivers say ‘rolling coal’ is for ‘idiots,’ but emissions cheating is a bigger Texas problem

Houston truck aficionados and environmental advocates agree coal rollers are an inexperienced, rogue minority of drivers who give diesel a bad name. But many who don’t roll coal do tamper with their diesel vehicles’ exhaust systems, often disabling the emissions control system or installing aftermarket defeat devices that help cheat emissions tests, as Volkswagen did in its scandal. The practice adds huge amounts of pollutants to the air, according to the Environmental Protection Agency.
Modifying diesel exhaust systems is illegal, but drivers rarely are sanctioned for doing so, or for using diesel smoke to harass or harm pedestrians, bicyclists or other drivers. Until that happens, the practice is unlikely to stop, officials and safety and environmental advocates say.