Noticed our neighbour across the street got himself a flat: had a tow truck at the end his driveway, and a guy working, pulling off the flat and getting the temp spare on. About 10 minutes later I opened our front door to retrieve the morning paper, and hear the low rumble of the tow truck, idling away. No lights flashing, it's just parked there, idling. From the time the guy showed up, to when he left, maybe 30 minutes transpired. I'm guessing it's diesel. Is this something they have to do, leave it running? Or just old school?