So Peggy has became an extreme gas chugger and I dont know whats going on. The Only events that have happen in the last thirty days, I moved from the DMV to Miami. I got another tired because the other had a bulge on it. and I recharged the A/C. While in the dmv peggy said that she was getting 23.0 MPG (before i had a/c). I did not drive her all the way down to miami we caught the Auto train and drove 260miles from orlando to miami. This was at the beginning of june. As the weeks have gone by I was filling up on fridays and by tuesday she was empty. right now it seems like its getting worse. please review photos and let me know what u think... shes taking all my money lol.

I would say that with my 97 PA it will average around town the same. 19.5mpg
You will consume more gas with the AC on as it does rob power away from engine.
More gas pedal is needed up hills or initial getting going from stops for instance.
What can you do to improve mileage? Move the cold tire pressure up to 36psi, remove all crap in trunk you don't need & do tune up.
When was the last time you changed the spark plugs & air filter etc?

Sounds normal to me, on Premium Gasoline your City MPG is only supposed to be 16 MPG, and Highway is 24 MPG, if you do a little driving of both then 19 MPG is about right, less than 19 MPG if you drive more on city roads, and more than 19 MPG if you drive more on the Highway.

You may get like 1 more MPG on regular gas, but I'd not run regular over premium just to get 1 more MPG...

http://www.fueleconomy.gov/feg/noframes/13620.shtml

I edited your tittle so other don't do a search and get mislead that you actually have a gas problem, as this is normal.

William, why would you be using premium?

But I agree on the mileage.....if this is mostly city driving, and running the A/C all the time, around 20 mpg is about right.....

My wife'* Bonneville would get around 30 mph on long trips to the Cape.....great for that size car.....City and hwy, it averaged around 25-26.....

But one time, we spent a week of local driving at the Cape, and mileage dropped down to about 22.....and that was without the A/C on....

P/A is a big car, and does not do well in stop and go, city traffic...

You can't really go by where the gas gauge is sitting, and even the DIC gives inaccurate readings sometimes. The most accurate way to test MPG'* is to fill up all the way every time you get gas. Then the next time you fuel, divide the number of miles driven by the number of gallons it took to fill up again.

The longer you wait (i.e. the more miles you drive between fillups), the more accurate of an overall number you get. Fillups between short trips may seem like really horrible mpg'*, in city driving and/or with lots of idling while running the A/C. But balance that out with any typical highway driving you do, and your numbers are probably okay.

If you had a significant problem with the car that was requiring/burning more fuel than normal, you'd likely have some other symptoms or warning lights.

So burning 6 gallons is normal in two day if i drove an estimated 118 miles on 6 gallons?

Premium doesnt help with a high mileage car?

I just bought the car a couple of months back from a guy who works on cars for a living, he has given me all the paper of everything he has done to it since he had it, and from what i can see the spark plugs were changed in 2009 @ 166,150 miles. And since moving down here i randomly see the tire pressure alert comes on, i checked them and they are at 40psi, should i removed the extra inflation?

I know it offers no real benefits, and may be a waste of money, I was just telling her what the listed MPG said, it says Premium gasoline.
Fuel Economy of the 1997 Buick Park Avenue

I use it because it is less combustible, and I get a little rattling on occasion which I figured was from detonation in the cylinders, since I have been using it I have not had it no where near as bad, I was not suggesting she use Premium, just going off of what I seen listed.
The older couple that I got the car from when it had 27k miles on it said they always used Premium, so I continued to do so.
Lately money is getting tight, so I may see just how my occasional rattling goes when I use regular unleaded..

Please check the tire pressure when cold first thing in the AM. If they are at 40 psi yes, I would reduce them to 36 max cold. If you look on the tire itself, it will have in fine print somewhere on the tire sidewall, inflation information. What does the tire say?
Regarding the spark plugs, back in 2009 ( 5 years ago they were changed) how many miles are now on the vehicle? I used NGK TR55IX #7164 Iridium plugs. I am about to change them again at 40 k miles, just because I am picky and want to see condition of plugs. A few years ago I also installed new NGK spark plug wires, were your wires replaced?
Re fuel I have 104k miles on my PA and I run 94 octane premium, non ethanol fuels where ever possible. This does give a few mpg better and I also clean the throttle body and intake ports once a year to free them from carbon build ups.