I don't usually tip taxi drivers very much because I view that as additional payment for something I am already paying them for, as opposed to a waiter or doorman.

Anyway, took the taxi from NYC to JFK . The driver was reasonably pleasant untill the credit card panel came up at the end of the trip. It pulled up one of those "automatic tip"windows and I was annoyed that the lowest tip was 18% going up to 25% (which is a lot on a $52 ride) this annoyed me a little so I therefore tipped him only five dollars, which is about what I usually tip anyway.

The guy got really angry and was pretty much harassing me, and claiming that he earned nothing on this trip.
I said nothing and got out of the taxi and it was obvious he wasn't going to get out to unload our suitcases so I had to open his trunk myself and take the suitcases out. (Would any of you have demanded the guy get out of his taxi and take our trunks out?) Being a nice guy I even closed the trunk for him.

Anyway what you think of all this ?

Do you give 18% or more tips for basically average service on a $52 taxi ride?