Funny, never seen the correlation OP is making. A/#1: many times the "aggressor" has tint dark enough that I can't discern ethnicity/race. B/#2: much of the time the "aggressor " is driving too fast for me to discern ethnicity/race. C/#3: I tend to keep situational awareness regarding the traffic around me and when I am in the left lane and can tell there is someone gaining on me, I move to the right and they rarely have to ride my @$$, not to mention I don't camp out in the left lane going the speed limit or slightly above. On the occasion that I get passed like I'm sitting still before I realize it is happening, I have seen no correlation with type of vehicle. Maybe OP notices what they want to notice(regarding type of vehicle, etc) and/or unwittingly invites aggressiveness by driving the speed limit in a passing lane (aka speeding lane). Maybe OP doesn't drive a truck and therefore has a bias towards them? Crappy drivers come in all shapes, sizes and colors (people and the vehicle they drive). I think it is more bias and generalization than trend.
That being said, why is it impossible for people to drive 40 mph on South College? You don't have to go 45 or 50 but 30 mph can get annoying