Hey man, that looks cooler than the clay render, but if you want to push it even farther here's a few more suggestions if I may....
-there are a couple places where it looks like you can see through the side of the truck through the window, on the last picture in particular.
-the lighting on the truck is about right, but the shaders need to be tweaked out a bit. Maybe a little specularity on there, have the sun reflecting on the windshield a bit or something.... Play around and see what you come up with.
-If it's sitting in the water, you got to have some ripples and reflections around the vehicle. It looks a bit like it's stuck on there.
-and the truck looks a bit lower in res than the background, i'd suggest taking down the res of the background pic from 300 to 72 before you do much more tweaking to it, or make your truck render a higher res.
That's all I got for now man, good work so far. Keep it up man.
-Z