There is several options for a V12 engine choice for the Germans in mid-1930s, before the new-gen engines are to be had:
- their own BMW VI (yes, it is a big engine, but it is/was installed in a few 1-engined aircraft earlier)
- buy at Curtiss, the Conqueror is of modest dimensions and weight
- Fiat A.30, or perhaps the bigger A.22 or A.24
- Hispano Suiza 12N or 12M, since the newer 12X or 12Y will be hard to obtain from France?
Note that neither of these engines has a supercharger, apart some prototypes.
Also note that all 4 new-gen German fighter entries were powered by Kestrel. Focke Wulf's entry was flawed in layout and in undercarriage, Arado's entry was with fixed U/C, Heinkel's entry was with a too big and thick wing (= more drag = less speed), thus it is no wonder the future Bf 109 won.
The Germans never intended to use the Kestrel in any of the prototypes let alone in production aircraft.
The Jumo 210 was running late and the Kestrels filled in.
BMW was also fooling around with a small V-12 The BMW 116.