I suppose you could say I used the sign for CAR because I used the classifier for a car

I promise I will let this issue rest soon, but I've got another question: does the above mean that there are unique classifiers for particular attributes of a car (e.g. a long car, a short car), which are distinct from, say, the classifiers for a stone column? I had assumed the classifiers would be common to all base words. That is, that there would be a single classifier for "tall" and it would be applied to trees, people, kolos, etc.

I think I'll go to the link you gave now.