[Blue)(Fusion]

The 98+ body style (aka "Whales") are heavier than the 92-97 models (aka "Aeros"). The weight difference is about 400 pounds and can affect mileage.

Also, you may have a different rear gear ratio than your 95. Check the tag on differential housing or check the sticker on the door. 2.73s are the standard for civilian models, but HPP and Police Interceptor models can have 3.27s or 3.55s. The previous owner may have had them swapped, too. 2.73s will give you best mileage at constant speed, but 3.27s or higher may actually give you better mileage if you do alot of stop-and-go traffic.

Plat plugs will not increase MPG because of their chemical makeup. Platinums are just generally the preferred plugs because they last a long time because they are harder and have a higher melting point, compared to copper plugs. If the plugs have not been changed yet, just go ahead and do it. I recommend sticking to Motorcraft plugs.

Some other things you might want to look into is make sure you're running proper tire pressure, the fuel and air filter are clean (replace if unsure), fluids, and carbon in the cylinders.

I'm sure you've checked all of the fluids already, but if anything looks dirty, change it. Dirty fluids don't work as efficiently as clean ones.

If the old owner didn't open up the throttle once in a while, there's probably carbon buildup in the cylinders. Do a Seafoam treatment in the intake system and fuel tank. Do NOT introduce Seafoam to the oil - some say it works, but I don't think it is worth my oil thinning out.

While you're at everything else, clean your MAF with CRC MAF Cleaner, and you may want to consider replacing your upstream HO2 sensors. These usually start to get lazy around 80-100k miles.