"Auto comparisons are just plain silly, not only because the operating conditions are so different, but far more importantly, motor car engines are built in the millions, justifying the development costs."
So how hard would it be to take one of the most reliable engines and qualify it for GA flight?
I read an article a few years back about a Honda Fireblade engine (918cc, 120hp) which they ran for a million miles. When they stripped it, all tolerances were within limits.
Now I appreciate this is on a test bench and the atmosphere controlled, but I would expect that many of the advances in plating, injection, cooling, materials etc. would be perfectly applicable to GA.
Why develop from scratch if you can take something built in the millions and just tweak it for your environment and qualify it...?