I like how the second one. It looks like it is actually made out of assembled pieces.
Maybe if you could make that one grey brick by the tire look more like the v0002 spray can? I dunno. Glass could use some work as well, and the main engine piece could either use fewer sides, or many more sides, depending on which way you wanted to take it. Right now its kinda in an awkward middle.
Anyways, its awesome and if I were one to download add-ons, that would surely be something I would be interested in.