Mileage improvents

[9723VF350]

Now that my wife is officially in love with her new 05 limited, it's here to stay for a long time. It has 190k on it, its 2 wheel drive, and it's a spotless, surprisingly tight southern vehicle. I plan on getting real about rustproofing, and it'll stay until it rusts out. I'm thinking 10 plus years and another 200k. The 5.4 runs perfect at this point. It's got new plugs, coils, and injectors.

Mileage seems pretty decent on it, 16-18 mpg. I'm all for taking something good and making it better though. She drives it pretty easy, rarely exceeding 2500 rpm. Here's a list of things I have in mind for potentially better mileage, I'd like some opinions if you guys don't mind.

It's getting 10 ply Michelins inflated to 80 psi unless i'm convinced otherwise.
Intake, several different manufacturer options. I like dry air filters.
Exhaust. My exhaust is perfect now, I see Walker makes a replacement muffler that is said to flow better. Cat back is also a option. I don't want significantly noisy exhaust.
Custom tunes. A economy tune and a towing (rarely used) is all I would need.
Lowering kit. I don't want it to look silly, but 2" would look fine and may or may not help.
High flow cats
Headers.
Diff fluid will be changed as soon as it needs a oil change and I put it on the lift.
Any other suggestions I'm overlooking will be considered.

Thanks.

 

[John Christopher]

I'm not familiar with Michelin 10 ply tires inflated to 80 lbs but I would think they are going to ride very very hard. The expo doesn't have a soft ride to begin with. I would make sure to get more info and try the tires if possible before buying. Your wife's rump could get awfully sore and you definitely don't want that. LOL

 

[autoarcheologist]

Go to ecomodder.com and look up what others have done with trucks. On the freeway a deeper air dam and possibly an upper grill block will help. Lowering 2 inches will also help a little with aero. At freeway speeds aerodynamic drag is your biggest issue.

A skinnier 245 or 255 tire should help, I don't think you need 10 ply. Just inflate to max pressure.

Can you swap the rear axle for a 3.55 gear instead of 3.73 if you have it? Lower freeway cruising RPM.

Oh and remove the roof rack cross bars of course.

Good luck, I plan to do something similar with our 2004 Navigator.

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[Hamfisted]

Wash and wax it. Properly inflated tires. Keep the speed below 70 mph. Use synthetic oil. It has the aerodynamic qualities of a large refrigerator going down the highway. Air resistance/friction and your speed are the most influential properties to your overall gas mileage. There's no silver bullet. Well, other than using a tow strap to latch onto the vehicle in front of you....



-Mike

 

[autoarcheologist]

We just took our Navigator on a 360 mile trip and averaged 14.8 MPG. Lol! Mostly 55-60 MPH. I'm going to have to work on that.

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