My first question I have came up upon seeing how many polygons this object has.

What is this going to be used with ?  I mean not in terms of models, but in terms of software. If it is a game, generaly speaking, games tend to make objects with the lease amount of polygon as possible.  If it is purely for rendering, then high poly  amount is the way.

Well I have never modeled nor looked at car models so I cannot give you a professional critic about it.

To optimize, you could try (don't recall if it is in GMAX or not) the Optimize Modifier and play with it.

As for design; your spokes are a little weak in that bend near the center of the wheel. Try adding a curved support behind that to strengthen up the design.

Critically speaking :) ; you could fine tune your mesh manipulation a little bit, but its a good start.

 

Cheers