Looks much more complete with the wheels attached to something!  Yeah, I've hit that ram limit before, it really does slow down the render a lot.  That's the reason I chose to make all the leaves in mine have the same mesh, actually, I have a tendency to over-detail things and then it takes days and days to render :(

I admit I haven't done much work on mine, I've been really busy this week.  I do like the idea of keeping this thread updated, though, means I might actually finish something ;)  Someone pointed out to me a few weeks ago that I only have one image in my gallery from this year....

By the way, have you discovered the new preview render?  I think it's shift+p in the 3d view, object mode.