Gas mileage HELP!

[Apache559]

2003 Mach 1 Auto 55,000 miles
I have these mods on my car,
SLP LM Cat-back exhaust, 4.10 FRPP Gears, Roy's Intake Spacer, Eibach Pro-Lowering Kit, K&N FIPK CAI, Maximum Motorsport Lower Control Arm, Tokico D-Spec Shocks and Struts, 18x8 front and 18x10 rear Saleens.

I'm getting ruffly 12.5 miles to the gallon in city and around 16 in highway is this normal with the mods on my car. i hardly ever get on it. very light foot, always under speed limit. I bought it a year ago and it didn't bother me much because it wasn't my daily but now it is my daily driver. I know if all i care is mileage i should have gotten a hybrid but i really love my car. im pretty sure my car has no tune with the mods it has. my car drives fine nothing wrong with it. With the mods i have would i need a tune to improve my mileage or go back to stock gears.

 

[4a7191a]

try some new plugs out maybe. ngk tr55's is what i run

 

[xXAzureMach1Xx]

Yea you prolly need a tune. Have a CEL on? Bad O2 will make you have BAD mpg. Nothing wrong with wanting the best mpg out of the car. Im not goin to not do something to the car just because it will get bad mpg but if i can get better mpg out of the same setup then i will try.

 

[clc44]

I would think a tune should help a bunch. I have JLT RAI, intake spacer, o/r x pipe with flows and I get 23 hwy and 18+ city and I get on it regularly(every few times I drive it).

 

[RcodeStang]

I get 18mpg mostly highway, best I've ever gotten is 21mpg pure highway. Considering yo have really heavy wheels, 4.10s, and an auto, yours seems fine compared to mine. The problem is that mine seems abnormally low compared to everyone elses.

 

[Apache559]

Not CEL on, and is there a way to tell if o2 sensors are bad by looking at them.

 

[clc44]

I have no clue on that man. Like said above, you have a lot of things going against good MPG lol.

 

[watman02]

auto or stick car???

 

[xXAzureMach1Xx]

CEL should be on if its a O2. Theres no way to look at it that i know of to tell if its bad. I get 17 city and 22 hwy with the eaton and when it was N/A i got 18 city and 25 hwy running 90 to 110 and then backed it down to 80ish and got 23 :shrug:

 

[xXAzureMach1Xx]

auto or stick car???

Says Auto oke:

 

[4a7191a]

also try the 3m mass airflow cleaner. that may help. i use it every time i clean the k&n. it gets gunked up over time. just be careful with the wires