Joe, I can only echo the others when I say how wonderful it is! For an old car, it has so such personality and life. This is really your best work, and amazing that it was an exercise. Perhaps there was less self-imposed pressure b/c it was an exercise. For myself, I find when I don't "try" to do something "good" I often have better results. We would all like to see more of these.
How long did this take and what is the size? Which paper and black watercolor did you use? This is really so good you should consider framing it.
BTW, we were on a cruise when Ian hit, and the itinerary had to be altered for safety reasons. The pax were all holding good thoughts for those potentially in harm's way. I am sorry that you had to deal with such a frightening experience.