Clearedtoreenter,
Whoa there boy, you might want to check your pea shooter before you commit.
Now granted computers and a electronics have done wonders for the internal combustion engine, but lets not forget the basic mechanical principals all herald back to the "30's" and there is not much new under the sun.
The basic design of the Lyc's and Continentals (or Nentals as some wag put it) or Rotax and Jab's for that matter is pretty bloody good.
Check out the BSFC's against an auto engine, you might be surprised. A properly set up aero engine at .39lb/hp/hr against an automotive engine returning between .42 to 1.0. And there's your emissions answer as well.
I'll give you the mag comment, and even constant flow injection is a little dated, but it works surprisingly well considering, as do carby's if you just want to run an engine in a narrow rev range, as we do. As for push-rods, well it's not a bad way of doing business in a slow revving engine, and oil consumption is governed by laws which remain unchanged since the 30's and apply to your Corolla just the same.
Both Rotax and the Jabiru's return very close to the same fuel burn /hp as do Lyc's and Nentals, when set up by a proper mechanic.
As a thought process strap your Corolla engine into a boat and run it near flat out. How far do you think you'll get?
There's a surprising amount to be learned from the olden days of suck squeeze bang blow wisdom.
M