I voted "real" based on a few things already noted, but I do think it's almost impossible to really know real from model when you get past the photoshop tipping point where more than half the image isn't really part of the source photo.
I'll grant it to Harry that it makes it harder, but I also think there has to be at least some integrity to the photo or the exercise goes from 'real or model' to 'spot the photoshop tweaks' pretty quickly.
Listen Mr. Grumpy pants...
I didn't do anything to this photo... it's exactly as I found it. Did somebody do some Photoshopping? Obviously. The background has been blurred. But as far as I can see the truck itself hasn't been touched.