It's not completely flat black now, there is some gloss to it. It's much improved from the high gloss, mirror-like finish Toynami originally had on it.
As for the wheels, Jed's repaint corrects them to how they appeared in Batman Returns. Black hubcaps with silver center Bat-caps. In Batman 89, they were gun metal colored, like the turbine engine (silver is too bright and flashy). Jed's repaint of the body and wheels makes it a much better representation of the Batman Returns styling than what Toynami originally had...all black hubcaps and black center bat-caps--a look that appeared in neither movie.