Put it this way, lets imagine that this picture was indeed very sharp and shot on a grainless film, or heavens forbid, digital. What would we have? A truck on a highway. Nothing more, nothing less. Sure, it might be a technically adequate picture, but I'd say it wouldn't capture the imagination of the average viewer.
Where's with this picture - the added grain, the blurriness - it adds tension. The way I am interpreting this picture is that either a violent storm is on us or approaching. I am not sure if this is what the photographer intended, but that is the feeling I get.