I have a really crappy car RomanSunburn and have made a lot of visits to my garage. He does the minimum to keep it running and I do my best to bring it in for the regular maintenance and slowly work through the recommended repairs. Maybe it's that he feels sorry for me, maybe it's my being a woman, but he has done things like throw in an oil change, replace my light bulbs, and repair a tire for free.

In return he gets a happy repeat customer. He also gets a lot of free advertising as I and likely other customers give him rave reviews.

It hasn't occured to me to read any additional motive into this.