So many years ago I use to be into SCCA autocrossing and track days. I had a '92 Saturn SC (the coupe). It was already fairly lightweight. But because it was only a 4 cylinder, weight was the enemy. I went through a lot of what you are doing because the less weight I had to accelerate, brake and change directions, the faster I would be.
So I removed the AC, I changed the power windows to crank, I took out the carpet and removed the Dynamat-like sound deadener stuck to the floor pan, I removed the back seat, removed the spare tire, took out the interior panels, bought light weight wheels, changed the metal power steering pulley to a plastic pulley, changed the driver seat to a racing seat and probably a few other things. I estimate it was down around 2100 lbs.
It was a daily driver.... for awhile. All those extreme measures to reduce weight also greatly reduced comfort. It more or less sounded like I was driving a tin can. I could hear the tires tossing rocks and sand into the bottom of the car. It droned at highway speed with all those interior panels and carpet missing.
And in the end, I saw little to no improvement in gas mileage. I know in theory, removing weight should help, but maybe it got lost in the statistical noise. Maybe the 5.4 will respond better to weight savings. But how much money are you thinking you'll really save by doing all this? Gas is cheap right now you'd have to drive a lot to see much return. Maybe at a whopping 37 I'm too old to think about driving around a vehicle like that anymore.
