Although Renaldo Balkman is nowhere to be seen in this video, it appears that this orange and blue 1983 Caprice Classic with multiple TV screens and "32" emblazoned on the inside of the trunk belongs to Humpty himself. I have no reason to believe otherwise.
That's our Humpty. Turns out my guess was incorrect, at least regarding this particular Knick.
Update: As Henry Abbott points out, Balkman's seems to be investing quite a bit of time and money into the promise that his career with the Knicks is a long-term affair. Just one more reason we should keep him around. Wouldn't wanna waste all that orange paint, would we?