the thing that followed my car on Route 77 — not St. Elmo's fire, I've seen that before

Okay so this is a old one but I need to write it down properly. My uncle drove trucks through the Texas panhandle in the late 80s and he swore on his life this happened near Marfa, out on 67 before you hit the viewing area they set up later. He said he was doing a night run and there were these two ……