The blind and the lame...
In this case it´s me who owns a scanner and Michael 917, who has all those interesting pictures and articles at home.
So he made some photocopies and sent them to me. Of course the results lack a little bit in quality, but I think, they are still good enough for our purposes here.
So back to the transfer of the cars from Italy to Germany:
The first picture is from Thoroughbred & Classis Cars, July 1996, and is clearly another shot from the same scene as on the photo posted by Michael Müller:
Turn your attention to the number plate: The car in front is IIA-57783, while that one of the car in the background is not visible, neither here nor on Michael Müller´s picture.
But in the same article and also in the already mentioned book of Rainer Simon there is another picture from the same "event", clearly showing IIA-57782:
As I said, the quality is lacking a little bit, but on the photocopy it is cleary that number on the plate!
And then Simons has also this picture of the third car, IIA-57781:
This picture is also mentioned in T&CC and they take it as a proof, that there were indeed THREE cars completed by Touring and that all THREE were returned back to Germany.
Quote: "The theory that there may have only been one Touring-bodied car from that period is blown apart, though, by the fact that all three were photographed together on their journey back from Touring to Munich. Two pictures, taken near Lake Garda, clearly show three cars on the trip. The registration numbers of two, IIA-57783 and IIA-57782, are visible; the third is obscured. The third car was in fact, registered IIA-57781: It appears in Anderloni and Anselmi´s book 'Touring Superleggera' with a pipe-smoking BMW-director alongside."
So for me it seems indeed clear now, that there were three such cars. Also Simons has a good explanation for the Munich number plates, as he states, that the three original BMW 328 roadsters were brought to Italy by the Munich NSKK squad.
Proof, that all three cars have returned to Germany would be if anybody could confirm, that the third picture shows indeed "a pipe-smoking BMW-director" and that it was taken at Munich and not in Italy, but I tend to believe that. What I still really wonder is how do they know, that the car with the invisible number plate on the first picture is indeed the third car, IIA-57781?
Perhaps anybody here around has access to that Anderloni / Anselmi book mentioned above and is able to clear the remaining uncertainties?
But now to the further fate of the cars.
I think, that I am quite right with my suspect, that T&CC mismatched Assenheimer and Rovelli in that article: "Touring-bodied car number one was modified after the war into a Formula 2 car and campaigned as a 'BMW Special' by Heidelberg-based driver named Rovelli. It appears in 'The Autocar' by Gordon Wilkins, dated July 1948. According to BMW, Rovelli´s car - distinguished by its bonnet intake and a lack of a central bonnet strip - was sold to an American buyer in the Fifties and disappeared without trace."
So if you replace "Rovelli" by "Assenheimer", "Heidelberg" by "Heilbronn" and "Formula 2" by "2 litre sports car" the passage will make sense again.
Michael 917 has already referred to this picture. It is the photo taken at the start of the 1950 Grand Prix, sports car race. The car in front, No. 28, is without any doubt Assenheimer.
But lookin at the picture again one question remains to me and I still wonder why he put that much effort in his car, replacing bonnet, front, radiator inlet, headrest and even a different-shaped side door (if I recognise that correct), only to form a car which is very much the same as the original?
Alongside him is Swiss Willy Daetwyler in a car which looks very similar to one of the NSKK Roadsters, but with an air intake on the bonnet that reminds very much to the cars of Rovelli and Loof. So another one of the series or simply a car, whose "producer" was only "inspired" by the NSKK Roadsters?
Here is what T&CC says about the other two cars: "The fate of car number two, in short, is unknown. It disappeared without trace either during or after the war. Number three, however, somehow found its way back to BMW´s Munich factory, where it gathered dust and was occasionally brought out for demonstration runs."
So no clue from that.
Here is what Simons has to contribute to this question:
"The cars returned to Munich on their own wheels. There they were parked at BMW´s initially. But shortly afterwards they were hidden on a farmhouse at the Tegernsee.
With help from former BMW employee Willi Huber one of these cars came into possession of Walter Assenheimer after the war, who slightly changed the styling of the car and gave it a silver coloir (it had been painted in red in the meantime). Assenheimer was an enthusiast BMW driver, but in 1950 he quit racing, pushed a little bit by his Stuttgart-based employer, which was building cars of another make.
With the Help of Egon Brütsch Assenheimer´s "BMW Spezial" (as he called it) was sold to America, where its trace gets lost. At least on of the cars (85051 - the first car that the NSKK had acquired) came back to the factory in 1945 and has survived until now as part of the BMW Mobile Tradition"
A few pages later Simons tells about some immediate post-war efforts of former BMW employees, Loof, Holbein, Dietrich, Meier, Huber: "The first roadster streamliner was destined for Sauermann, the second to Holbein (later to be known as the HH47), the third was for Kling.
So it is no accidental, that the bodyworks of these three "Specials" remind very much to the three ONS (sic!) Roadsters, which had been produced by Touring in 1940/41. Indeed one of these cars had found its way from its hiding place at the Tegernsee to Huber´s garage in the meantime."
Two of the cars mentioned here can be seen on the next pictures, first Holbein in his HH 47 at Hockenheim, 1947:
and here is the car of Kling at Hamburg in the same year:

:
But what about the third car? To me there are three possibilities:
* It is in fact the car, which went to Assenheimer - very unlikely regarding the upper lines of the car, which are very more like the NSKK Roadster than the Kling and Holbein cars, so I would exclude that.
* The car is identical to that on the picture showing Loof in 1946 (see above) - unlikely to me, as the BMW "kidneys" seem to have been already out of fashion, but still a slight possibility
* The car is what later became known as the first Veritas, the "Großmutter" and remained with Loof, which is my favourite version.
Here is a picture of the Großmutter from 1949, driven by Ulmen at the Schottenring (the car in front):
I think, that looks very similar.
So that only leaves the Rovelli mystery to be treated.
Simons tells, that Rovelli was former Touring employee and converted the car by himself. And T&CC has this picture:
Is this really the Rovelli car??? T&CC themselves are not very sure about that: "One of the Touring trio, probably Rovelli´s, on test." If my understanding of all, that was written here is right, then Rovelli used the car in "NSKK-"spec only once and then converted it to an open wheeler. But on the Piacenza picture there seem to be some additional air intakes on top of the radiator, so I think this is not the Rovelli car.
But what is it? Is it the Assenheimer ? Unlikely, as this would have meant a second conversion of the air intake. To me it looks very much like the Daetwyler car in the picture above. But it could of course also be the Loof car, or even both cars could be one and the same!
Any answers to that question?
And Michael, thank you again, for those very conclusive pictures! You see, they helped us a lot further!