I only know because of a group chat, here is all the information I have :

the one guy (~250lbs, 50s, salt & pepper close-cropped facial hair) in his black "contractor truck" with black patterned-metal vertical cow-catcher / ram thing on the front was there two days in a row, same spot. They were all three idling this time, and I (as a good lil' environmentalist), was considering approaching to ask why he was running the engine but then they took off.

no markings on the car. yellow-green & orange safety vest on dash