Rolling coal has been around since heck was a pup. You can find some videos on YouTube. There are all sorts of targets for the smoke (including cops) or none at all and most get a ton of angry ecowhining in the comments. Here’s one from 4 years ago featuring a logging truck and bicycle riders - http://www.youtube.com/watch?v=ZdDxjge5hmY
There *IS* such a thing as gratuitously making enemies, though.
“Here’s one from 4 years ago featuring a logging truck and bicycle riders”
Wow. That guy is an a**hole.