2001 Saturn SL2 DOHC AT noob questions

[questionful]

Hello, I'm 18yrs old and I recently got my driver's license. The car I'll be driving most is a 2001 Saturn SL2 DOHC AutoTran with 136k miles. My priorities while driving are 1)Safety, 2)Car Health, 3)Fuel Efficiency or something like that. So I would like to put some effort into making the car more Fuel efficient. I've been thinking about some things recently.

I never use the air, heater, AC, and whatever. Could I remove a bunch of that stuff and increase efficiency?

I am considering changing the wheels to bigger ones. This would reduce rolling resistance and let me go faster at the same RPM, but it would also increase spinning momentum and it might risk lugging the engine. Also, going faster at the same RPM would increase drag.

I am also considering changing the highest gear to a slightly higher gear. But this would also be for the purpose of higher speed which means less efficiency.

My highest gear runs about 1500 RPM at 35mph. Is that my most efficient cruise? It runs 2200 RPM at 55mph, which is what I usually limit myself to.

I am considering designing and building a custom air intake. What would be the most efficient air intake? Considering that the car might need more power to accelerate a car with larger-than-stock wheels, might a cold-air intake help improve efficiency? I was considering making an air intake with a huge valve to switch the intake from below the hood, on top of the exhaust headers, to above the hood, in a hoodscoop. So basically by installing some sort of cable switch, I could switch (or even fade) between a cold and warm air intake depending on current needs.

Most of this is basically daydreaming. I just wanted to get some basic advice. Thanks.

[JasonG]

I never changed the tires on mine and am not sure of how much clearance the wheel wells have.
That engine is very temperature sensitive. A warm air intake will help FE while a cold air intake will lower it.
The 5th gear swap is popular, never did it but a few have had good results.
The SL/SC saturn had very flush windows. Rolling them down is worse for FE than the AC is.
Leave the heater. It doesn't hurt FE but is needed for keeping the windsheild clear for safety reasons.
They can handle an upper grill block as long as the radiator is clean and you don't live in the desert.
For a minor increase, space the headlights forward until they are flush with the hood/bumper.
The rear bumper is a parachute and needs a belly pan.

I miss mine It was T-boned but its side impact construction saved my wifes life.