A person that drives in the passing lane (left) slower than the traffic on the right. They will not move over, but they will however speed up to prevent others from moving into the lane s/he is in. They are the really slow drivers in the middle lane of a freeway. In addition, Detroit Drivers do not like to allow on-ramp freeway traffic to merge into the lane they are driving in, even if they are behind the merging car. Most importantly, they will appear to drive without being aware that what they are doing is rude.
You can watch as this phenomonon dissipates as soon as you leave Michigan (esp the Ohio border).
There he goes, another Detroit Driver, won't move over so we can pass, but look at how he sped up when you tried to pass him on the left.
Detroit Drivers do not even know that the left lane is for passing traffic.