I think Ifound it. This car took part at the "Grand Prix des Frontières" ( it happened to Chimay, a small town near the french border... ) in 1946. The car has been specially made - I believe - for this race, so I suppose the car is from 1946 too.
Yes. One point to you.
It appears that the car was built during the later years of WW2, and was thus ready for the 1946 season. It was constructed using all sorts of parts, but the chassis was Ford, and the engine was a 2.3-litre 6 cylinder Steyr. (Sorry PJ - I know you asked about Austria, so when I replied I said the car was not built there. Life is tough in the Pros!).
I cannot find any reference to the car taking part in any other races, although maybe it raced in lesser Belgian or French events which are not on record. The car still exists, and has had the front modified to look more modern. (My Pro puzzles never last long, even when I think I've found a good one!)