Fuel mileage help

With my 92 DeVille after a good tune up, checked spark advance when you could, was only averaging 23 mpg, was way in the heck off, suppose to be 10* BTDC, was set at 3* AFTC, and you have to pull a plug to disable the spark advance first. Since I was using ethanol free 91 octane fuel, set it to 12* BTDC, on the highway, shot that up to 32 mpg.

These later vehicles use a knock sensor, so the higher the octane fuel you use, the better the fuel economy, more spark advance, extends the combustion cycle.

Always used a low spark plug gap, using 25 mils on the Cruze, compression tuberlance is a problem for blowing out a spark. Another is a misfire can cook your cat.

In my town, Mobil gives me the best fuel economy, son in the next town asked me what I was using, his Mobil station was terrible. You don't know what in the heck kind of fuel you are getting anymore. Have to try different stations.

38.5 mpg surprised me on a recent 380 mile trip using winter gas driving 72-77 mph, so I wouldn't get ran over. 46 mpg if I can hold it at 62 mph with summer gas. One trip on a deserted Wisconsin road, averaged 57 mpg driving at 30 mph in 5th gear.

2012 2LT with a manual transmission. Cruze brakes were not made for road salt, constant problem with those metal clips on top of a very poorly plated pad bracket forms a pocket for rust built up expanding those clips locking the pads. Do a frequent walk around have driving a bit with the back of my hand at each wheel. If you feel excessive heat, have problems.

04 Cavalier did not have this problem, should have stuck to these brakes.

Car is perfectly stock engine wise, adding sill plates is the kind of mods I made to it. Running Autolite double platinum APP3923 plugs gaped at 25 mils. Clean them at every 15K miles, getting close to 45K miles, purchased new ones, darn near twice around the earth is enough for any set of plugs. Only use ethanol free 91 octane fuel in hopes that the price of groceries come down so we can afford to eat again. Fuel bill is not even close to our grocery bill.

Only use top tier gas, but still dump in a can of Seafoam in a full tank of gas to help retard that carbon build up. Make sure the air filter is clean.

Definitely want to keep the air filter clean/replaced often if running factory style. Might want to run a fuel system cleaner through it too, with some 91 octane or better. Make sure your front/rear brakes aren't dragging, because I know there were threads here about the rear drums not being adjusted properly from the start. As stated earlier too ... re-gap plugs to .028 as that's where I noticed the best improvement in how the car ran and didn't hesitate when starting out from a dead stop. Maybe want to run some gas line antifreeze through the tank too, because depending upon how much water is in the tank, it might be affecting your mileage too, although it would have to be a good amount of water. Then again, I've seen cars turn a corner and have their exhaust spew water like the car had just come out of a car wash! That can't be good for mileage numbers increasing.