Outside of hobbyist circles (may their brains match their guts), car engines in planes have a rocky history. There was a big push in the 1990s to put "modern c

Outside of hobbyist circles (may their brains match their guts), car engines in planes have a rocky history. There was a big push in the 1990s to put "modern car engines" into GA planes, mostly diesel. It ... didn't go well. Turns out these car-derived engines were a lot less reliable than the good old Lycoming IO series, and much more expensive to maintain due to higher complexity (not to mention heavier, which always is a concern with airframes). And then there was the question on how long the manufacturer would provide replacement parts... There is a push to make car engines happen with some EU-based manufacturers, most notably Diamond Aircraft, today. We'll see how that works. Add that to the fact that new aircraft are prohibitively expensive, and we'll see manual mixture control-based engines for decades to come.