Actually, it's not.
I was in an accident almost exactly similar to this. I was doing 70 down a highway and a driver pulled an illegal U-Turn along a 4 lane road and ended up in the far right lane, pulling across all 4 lanes to get to the far left lane again right in front of me going about ~15-20 still. I had less than a second to react to him suddenly serving across all the lanes and smashed into his side and went flying over top, exactly like this. I even remember muttering the exact same 'oh shit' under my breath.
/u/S-Array03 was entirely correct, it wasn't one of fear, but disappointment. I at least honestly thought I was going to die and just closed my eyes to accept it, and the oh shit before was like a, 'wow this is how its happening, huh?' I definitely wasn't scared, at least personally. It happens too quick to really fear that kind of scare imo. Friends who have had severe crashes all share similar experiences. There's no terror in that final moment when you realize it's too late, it's just an annoyance/disappointment that this is going to happen.