If you haven’t seen this, they are called “Coal Rollers”

Rolling coal is a form of anti-environmentalism protest to put it nicely. It is done by removal of the particulate filter on a diesel engine which then enables the driver to emit huge amounts of black sooty eshaust fumes that have not been completely combusted by the engine. Oftentimes times smoke switches are added to the car as well as oversized exhaust pipes or smokestacks. These modifications can run from $500 to $5,000. So not only is this an anti-environmentalism protest (by an asshole) it is also actually polluting the air in a huge way. Oh and if you happen to be behind one of these cars it can also be extremely dangerous as your vision can be completely blocked.