I saw the same thing...ONCE in my life, but an obviously different situation.
I was traveling east on I-80 about 20 years ago around the Indiana/Ohio area. It was about 2-3 am, and I was doing well above the speed limit trying to get from Iowa to my home at the time in Canton, OH.
I was around 20 mph over the limit cruising along on what was a nearly empty interstate. Suddenly, three black Suburbans FLEW by me with just headlights, and no running lights. Then a black semi with something on a flat bed trailer fully tarped in black, again with only headlights, and no other lights...then followed by three more black Suburbans. They had to have been going 120+ at least. No way was I going to catch them to tell them to turn on their lights, and I honestly am 100% sure it would have been a possibly lethal event if I even tried. It was one of the top 3 spookiest things I have ever seen in my life...gave me the creeps.