[Setec Astronomy]

Johnny, open-loop is rich for a number of reasons, one of which is your "air" questions. If you take a glass of water with ice in it outside in the summer, it gets condensation on the outside because it's cold enough to condense the moisture in the air which is in a vapor state in the warmer air. As you probably know, liquid gasoline doesn't burn, it's the vapors that burn (hence the lighter fluid trick in those car polish infomercials). The fuel has to be vaporized to burn in the combustion chamber, and when the car/ambient is cold enough, the fuel will condense on the inside of the intake manifold/etc. before it gets to the chamber. That's the reason that those old carbureted cars heated the intake air, to help the fuel vaporize and stay vaporized until it got to the chamber. This problem was largely mitigated by port fuel injection because the injector is moved essentially to the valve port and is squirting on the back of the intake valve.

An internal combustion engine is a heat engine, it's all about the heat, if you lose the heat out of the system, you lose the efficiency. The heat in the expanding gases drives the pistons, some of that heat is lost to the block, etc. Smokey Yunick used to rant about if only he could build a ceramic engine (so it wouldn't melt) that didn't need to be lubricated (the lubricants have a temp limit) he could keep all the heat in the engine instead of it going out the radiator and tailpipe, and he could get great mileage because he could get all the energy out of the fuel instead of wasting most of it. A car has some ridiculously low efficiency after you factor in all the heat loss and all the gear, bearing, and tire friction.