And in case anyone thinks that this is a niche thing, I have been "coal rolled" on the sidewalk multiple times in Indiana and South Dakota. I'm not saying it's common but it's definitely an activity that a number of people enjoy.

These vehicles are in violation of emissions controls and are subject to revocation of their registration. Feel free to report them to your state dmv. Photographic evidence should be sufficient.

In other news the black soot of diesel exhaust is a powerful carcinogen. People who do this are willfully poisoning people so don’t worry too much about calling them out.