Dictionaries are not end all authoritative sources. They often do not keep up with slang. As a native English speaker I can say that "pimp" has both that usage and the usage coined from "pimp my ride". I don't have hard numbers on that usage of pimp, but I believe that it's entered the public lexicon at least for my generation. I don't think anyone my age would be confused by that usage.

You are technically correct, and also wrong at the same time by insisting that the way people actually use words in real life is "wrong" because the dictionary says so. If people use "pimp" in that manner, then it is correct.