Worksim, what's the poly count of that model with wheels?
I suggest making that builder's plate on the cylinders out of a texture with bump map instead of having physical lettering as that eats up alot of polys for a tiny part. Otherwise, it looks fantastic. Perhaps you could also consider releasing an object version "as-is", without the wheels to make it look like being under repair/refurbishment? Would be nice to have sitting around some engine shops.
Cheerio,
Nicholas