Re: Why were inverted V12s popular with the Germans?
It's partly for packaging reasons and partly also accessibility and survivability. It's easier to replace fluids from an external tank with a feed pump than spend time mucking about and armoured lines and tanks are lighter than armouring a whole crankcase - you can also have aux lubrication circuits when you need them.
IE almost all aero prop engines have two entirely separate ignition systems (as did the BRM V16, bad idea). Mostly they run on both (which also aids power) but if one distributor or magneto went south, you've still got a running engine. The A10 ground attack aircraft has no less than three hydraulic-electric control circuits, AND a fully manual rod & joint type which one American was very happy for when her plane got badly shot up - she managed to get it back home but I'd imagine she wasn't feeling all that happy about 48 hours later - a lot of pulled muscles, manual means manual on those. No hydraulic pressure probably means no flaps or brakes either..