[SFfiredog]

The famous Damlier Benz DB 601/605 and Junkers Jumo 211/213
inverted V engines were marvels of engineering.
As Fred stated, the advantage of having a 20mm cannon firing (MG FF, MG 151 and the later 30mm MK 108 used in the Me 109 K series) through the prop was important but the inverted engines were introduced long before the centerline cannon was used.
The main reason for the inverted engine was the lowering of the thrust line in relation to the airframe. The lower center of gravity, which is closer to the central plane of the wing made for superoir flight characteristics. As far as armament placement was concerned, the inverted V configuration was more important for the cowl mounted machine guns, which every fighter aircraft built by the Luftwaffe had. The inverted V allowed more room in the upper cowl area, alowing two 7.9mm and later 13mm machine guns to be mounted tightly against the sides of the engine.
As far as prop clearance is concerned the only German inverted V that to advantage of this would be the Argus V-8 and V-12 used in aircraft like the Messerschmitt Me 108 and the Focke Wulf Fw 58 and Fw 189. The props were driven at crank speed and had no reduction crankcase. The Me 109 series and later Fw190D had a crankcase reduction gear that LOWERED the prop closer to the ground. Check the landing gear length on a Spitfire compared to a Me 109. The 109 gear legs are at least 50% longer due to the lower prop.
As for the automotive uses of an inverted V, I would say none,
especially in front engine configuration. Even with engine set-back, where are you going to put the suspension and steering components? in a front engined car, wouldn't placing the trans (specifically, trans weight)i n the center of the V destroy the weight balance?Where do you install the clutch? An inverted V engine has 5 piston rings, 2 below the piston pin and 3 above the pin in order to seal the cylinder. More piston weight. Not a problem on a 2600ci engine that only revs 2500 rpm. The questions are endless. I think if it were a viable alternative, someone, like F1, would have already tried it. In my mind having the crankshaft centerline up near the windshield is not such a good idea.
JMHO,
--Mike