Also, I sort of live out of my car so I bet I'd get better gas mileage if I packaged my stuff better and took it out whenever I could.
It's pretty unlikely that weight reduction will help your car. Big, torquey, tall-geared American cars generally don't produce any results from weight reduction. If it would help, it would have to be a lot; your car probably weighs 3500 lbs or more; taking 100 pounds out will never make a difference.
What does acetone do to improve gas mileage? I read the gas log of the car that someone posted, and the driver mentions acetone...
Gas additives like acetone are generally credited with changing how the gas burns so it will burn more efficiently. I'm skeptical of most but open-minded. However, I'm also fearful of damaging stuff by putting various abnormal chemicals into my fuel.
the idea of the higher vacuum is for cruise only. The idea is the higher the vacuum indicates less throttle. There will always be pumping losses especially in an older engine But i've seen 32mpg in my mom's 87 Buick Lesabre driving with a light foot.
What engine does the Cavalier have? That 2.2OHV is what I would call the little brother to the 3800. It has plenty of torque down low for in town driving and don't see 100 pounds making a measureable difference in that case either.