I realy like, what I am seeing here. Good job man.
My only sugestion is to take care of the large parts of the object further (the weel is superb, but is it going to be noticible?), and made much more details in there (like this rounded front part).
I also like your medusa from the previous contest.
If you are not yet, take a look on this stuff...
It helped me a lot. I think its worty of thinking on that way while you modeling.
Good job, again.