[101Volts]

I got this car at 153k miles, and I was getting about 14 MPG. I raised the Tire PSI from about 30 to 40 & used Amsoil Performance Improver. That made a good improvement, I think the injectors and valves were dirty. That's just basic stuff, though.

In Mid June 2021, I replaced oversized tires with the right sized tires. For a while, that made a 1 MPG increase over the old ones.

As of September 2021, I was getting about 20 - 21 MPG with minimal mods, but EOCing wasn't the best idea.

In October 2022, I added a 600w block heater. I also re-added the WAI tubing, and the grill block. The car has been getting 18.1 - 19.1 MPG, according to the on-board meter (which is accurate.)

Specs:

Auto Trans
Ford 4.0 Engine
Stock Mechanical Belt-Driven Engine Fan (ouch.)

Fluids:

Amsoil 10w30 Oil
Amsoil P.I. (Performance Improver [Injector and Valve Cleaner]) once a year, minimum.
Amsoil DOT 3 Brake Fluid
Unknown ATF (I'm not changing it, for concern of trans failure.)

Differential (Gear) Oil:
??? 75w90 Front,
Mobil 1 75w140 Rear.

Mobil 1 is the thinnest Gear oil (in those viscosity ranges) that I know of, and I expect it to slightly push fuel efficiency in my favor.

Gasoline Mostly Used: Top Tier Gasoline, E10, 87. Usually bought at a Citgo station.

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Mods:
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(Mods last updated 2022 - November - 9.)

Aero:

Air Dam (Floor Mat attached to the existing Air Dam. Goes down to 5 inches above road surface.)
Roof Rack Delete

Engine:

600w Block Heater
Grille Block (3/4)
Warm Air Intake (Cold Air blocked, hole in air box added, clothes dryer ducting added that goes to exhaust manifold near oil filter.)

Driving Behavior Mods:

Alternate routes in town (traffic permitting,)
Driving a bit slower,
Engine off at lights,
Timing lights.

Tires:

Cheap, Stock-Sized Tires: 235/70/R16,
Tire PSI (Read while Hot) is: 45 Front, 49 Rear.

Other Mods:

3rd Row Seat Removal.

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Planned Mods:

Heat Retention
Wheel Skirting, Partial Front Wheel Skirting & Partial or Full Rear Wheel Skirting

Considered Mods:

Electric Fan - Not sure what to do here. Maybe use a fan off a Taurus or 95 Mercury Cougar. I expect this would be a 2 MPG Increase.
Indexed Spark Plugs - Just a little detail in the big picture. Probably good for 0.1 - 0.3 MPG.
Partial Kammback

Less Considered Mods:

Power Steering Delete - 1 MPG, maybe?
Manual Transmission Swap - Some 2002 - 2003 Models came with a Manual Transmission, and there are guides to this. It might help by 2 MPG or more.
Re-Tuning - Not sure how much this would help.
Water-Methanol Injection - Requires re-tuning the engine to make use of this. This might be a 3 or 4 MPG Increase, but it also includes extra parts, and extra fluids to use.

Mods I'm Against Doing:

Side Mirror Deletes - I once had a far too close encounter with someone who nearly side-swiped (more like rammed) me from a highway on-ramp to consider this. If I didn't look in my side mirror the very second I did just as a habit, I wouldn't have slammed the brakes, and they'd have barreled into me at about 75 - 80 MPH when I was going 50 in a 55 zone, with no-one else on the road.

- Austin