When I stop for gas at a full service station I get out of the car to schmooze with the attendant- nothing too deep, just like “How’s your day been going so far?…” (If it’s really cold outside I offer them to sit in the car and warm up while the car fills up (only one attendant ever took me up on the offer.))
When I’m done I give the person a dollar. The one dollar means much more to him than it does to me. (You should see the look of appreciation on some of their faces. For the $50 to $100 a year this tipping costs I think it’s worth it.)
One guy at a station on the NJ Turnpike made a mistake once and couldn’t stop apologizing. I felt so bad for him that from then on I always made sure to stop at that rest area and pull up to the pump that he was serving. If he wasn’t there I asked the attendant who served me to send him regards (he would usually let me know on my next trip that he got the message). I kept up with him for a few years until he got promoted (to fork lift operator at the warehouse) and switched locations.