your post is very informative and discuss about one of the most strange part of the mystery. If you follow the tyre marks it's quite impossible to explain that big dust cloud, which imho is totally unmatchable with a complete 360 back to the front spin, it's impossible and you don't have matching marks on the asphalt. Given the pic we have about the point at its days imho the only explaining is that the car did pass throught the dust/terrain/greenish portion of the road that you can see in this pic, on the external right side of the point
but... the mystery returns, because there wasn't any mark of the wheels in that point, so the only reasonable explaining is the that big dust cloud is the result of the S4 touching the little portion of the grass (and the terrain below) near the exit point, when the tyre marks touch the green (you can see some changing in color here, a pic who has been previously posted in this topic, the green becomes yellowNäytä liitetiedosto 3417
. It's very very strange just the same, because that dust cloud is very big, but we are at the starting point again, because if you imagine the car touching the dustier portion of the road than, as we said, you don't have marks and you can't explaining the marks you have instead. In this pic you can see some other mysterious blackish dark terrain marks in correspondence with the starting of the right rear tyre mark)
as for another unclear thing, the terrain in the actual point in which the car went off, and its direction, the only explaining I can see is something I've already written here, imho the S4 went oversteer (or, for some reason, exit the road with a left to the right direction, which is could be matched with the car pointing opposite direction after a countersteer, and could be matched with the strange "right to the left" direction with whom seems to fall after it went off the road). Tyre marks are compatible with a 4 wheel oversteer after handbraking also, because with the differentials of their time, and given high speed, car shouldn't had block rear wheels only.
The most easy explaining of the crash, the car exiting following the straight marks (going off and falling with his right side) is imho totally incompatible with the video which shows the car with a from right to the left to down line, and the terrain mark in the point where the car is supposed to fall down.
this said, your reconstructed full view of the scene is great, it would be great, with someone who can use graphics in a proper way, trying to do a "google maps look-alike" reconstruction that could be turned and moved in 3d, so you can see where the car is in a clearer way.