1
general::
Phrase(s): road hog
Fig. someone who drives carelessly and selfishly. • Look at that road hog driving in the middle of the road and stopping other drivers from passing him. • That road hog nearly knocked the children over. He was driving too fast.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
A motorist whose vehicle straddles two traffic lanes, as in Stay in your own lane, you road hog! This expression uses hog in the sense of "a greedy or selfish person." [Colloquial; late 1800s]
American Heritage Idioms