Show your gratitude to a great mechanic with loyalty and referrals, not with a tip

Dear Tom and Ray:

So, should you tip your mechanic? Would it be insulting? Would it be appreciated? How do you know how much you should tip if, indeed, you should tip at all? I ask because recently I went to a mechanic I found in The Mechanics Files on your Web site. I had two problems. No. 1: I had a nail in my tire (turns out it had not created a leak, but they spent some time searching to be sure). No. 2: My engine was dying at awkward times, and they discovered that a little hose that connects the vacuum sensor had a tear, and replaced it. They didn't charge me a penny! When he told me this over the phone, I was astonished. They get paid a lot for their time, and they could have spent that time earning money by fixing someone else's car. I decided to insist they take some money. But when I got there, it occurred to me that it might seem ungrateful of me, or insulting, so I chickened out and thanked them too many times and left. The next day I brought them a homemade chocolate cake, and thanked them again. But I wonder if I'm ignorant of some code or courtesy that would make a tip appropriate. Please advise!
-- Kyleleen

Tom: What you did was perfect, Kyleleen. A mechanic might be uncomfortable accepting a cash gratuity, but no one will ever turn down chocolate cake!

Ray: Wait, Kyleleen. How do you know these guys aren't just lulling you into a false sense of security? And setting you up for a $4,000 transmission rebuild next month? That's what I would do!

Tom: That's why no one brings you cake, you knucklehead. Mechanics and tradespeople usually are not tipped, like waiters or taxi drivers are. This is especially true in smaller, independent shops, where the mechanic may also be the owner.

Ray: But that doesn't mean you can't express your gratitude. The best ways to do that are by (1) giving a sincere compliment, (2) becoming a regular customer and (3) recommending him to your friends.

Tom: An honest "thank you" and an expression of appreciation means a lot to a mechanic. Think about all the complaints we get, most of the time. We encounter a lot of suspicion and wariness from our customers -- and rightfully so! But when we do a good job, it's awfully nice to have someone smile and tell us how much they appreciate it.

Ray: Especially when it's sincere. And remember, nothing says sincerity like baked goods!

(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk Web site.)