Gas Mileage?

[ZACHSTER22]

I recently purchased a 97' Bonneville from a used dealership down the way and so far everything has worked just fine, smooth ride (much better than the 69' Chevy C-10 I was puttering around in). But i've noticed my gas consumption is almost the same as the V8 I was driving which was getting around 8-10 miles a gallon. I'm supposed to be getting around 18-19 in the city. The air filter is new, the oil is fresh as far as I can tell. What is going on? I was told a tune-up may be the fix, but I'm no mechanic. If you need any more information to help just ask and I will provide it.

[Jrs3800]

You need to do the basic maintenance first... New plugs, wires, PCV valve... And possibly a New O2 sensor...

How many miles on the car?

I have 3 Bonnevilles, and none of them do less than 18 in town... Heck even my Modded 95 Pontiac Trans Sport does a worst of 16, and thats with 3.33 gears and a lumpy cam toting 4000 Lbs with me in it....lol

[ZACHSTER22]

It has about 103,360 miles on it, I'm off by a hundred probably give or take. I got a tune-up a couple days ago. So I have premium wires and spark plugs now. Me and a buddy went and got a fuel filter today, so we are going to jack up the car tomorrow and install it. How do the PVC Valve and O2 sensor contribute to the possibility of lowing my MPG? Forgive me, I'm not a mechanic