You could save a lot of polygones if you detached the extruded parts on the sides and made the inside face (the face they were originally extruded from) into one flat piece.
tha back looks like it would be a half track.. the front a truck with a spaceshuttle type nose cone. I admit it is unique but looks very Landish in design and not very .... sea worthy alot of those points and body shell designs wil cause "drag" against water.... not a good design.