While my gut instinct tells me to get the 5.4 in my new truck, I'm still leaning towards the 4.6 Both are very durable engines. The only thing holding me back from the 5.4 is the mileage.
If anyone could give me an idea of what kind of mileage to expect with either engine it sure would make the decision that much easier.Thanks in advance.

 

About 17. I can get 19 to 20 if my severe case of leadfooditist isn't acting up I have the 4.6 only because the 5.4 isn't offered in manual.

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97F150 XLT SC 4x4 Flairside 4.6 V8 5sp Dk Toreador Red, 3.55LS
ARE tonneau cover, p255/70rx16 tires (came w/235), Superchip
Pioneer CD w/4 Polk Speakers & Clarion APA5240amp, skid plates
bed liner, side window deflectors, reese hitch, K&N air filter
40s-2chamber Flowmaster, Bosch +4 spark plugs, rustproofing
Better Built Stainless nerf bars

 

I faced the same dilema when ordering my 99 F-150 SC. So, I went to my dealer and test drove both the 4.6 and 5.4, with as much similar equipment as possible. That was all it took to convince me to go with the 5.4. There was (in my humble opinion) a noticable difference in torque and acceleration. From what I gather, the difference in gas mileage ranges from 2 to 3 miles per gallon. Anyway, driving both of these V8's back-to-back should give you a feel for what each of them can do. Most importantly, go with one that fits what you're looking for - I wanted raw passing ability on the highway, with an occasional need for heavy towing. Open-er-up and hang on!

FastWilly

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99 F-150 SuperCab Lariat Flareside; Amazon Green/Gray two-tone, 5.4L V8, Class III tow package, 3.55 LSD, Rear Sliding Window.

 

I have a 99 F150 w/the 5.4L. With 2000 miles on it so far, I allways get between 12.5 and 13 mpg. It takes me about ten days to burn a tank of gas. I take lots of short drives. I think it will get better gas milege when I drive it on the highway.



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'99 F-150 XLT SC 4x4 5.4L Auto 3.55LS Tow pkg skid plates , Superchip, Gibson cat-back, K&N filter w/ airbox mods

 

I average between 17 and 18 mpg. most of my driving is highway. at present the truck has 7400 miles on it. running synthetic motor oil. after it goes to the dealer next week I'll change the trans, transfer case, front and rear end to synthetic.

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99 F-150 XL 4x4. RC Flareside 4.6 5spd, 3.55LS. gibson 3" cat-back, K&N Gen ll.Westin step bars.Ventshade window deflectors and bug deflector and a cool white shifter ball. The SILVER BULLET. Rock and Roll...Baby!!!

 

The axles come from the factory with synthetic lube already. Don't bother changing them out, you should never have to unless you get water in the axle.

 

I recently purchased a S.C. 4x4 with a 5.4 I have 1200 miles on it, I went through my third tank of fuel my number so far are:15.1,15.8,15.2mpg depending on how much I run the a/c. The lower numbers were with the air running most of the time. Most all of my numbers are highway miles, 25 miles to work then back. I am light on the pedal though, If you get into it I can see that the mileage will be reduced. There is a toss up, a great deal of horse power and torque differance between the two. If you don't plan to do a lot of hauling the 4.6 is a great engine, if you do plan to haul of just like to know that you have the the largest engine get the 5.4. On thing to think about also is at least in my state, you can get much more on trade in or outright sale with the largest engine available for the vehicle. I don't think anyone could go wrong with either engine.

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1999 F150 S.Cab 4x4
Northland Edition,5.4
Off road pkg. Fleetside
Black w/grey int.

 

I'm getting 14.5 in the city and 17.5 on the highway running AC continuously. I drive very easily though, no racing, no pulling, etc. Haven't even stuck my foot all the way to the floorboard yet and have about 1200 miles on my truck. Get what you want and you can't go wrong!!

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1999 Ford F-150 XLT Sport 4x2 SC; Black, Med Graphite Interior, 5.4L, 3.55LS, 17" Wheels, 275/60 Tires, Tonneau Cover, Captains Chairs, CD Changer, Heavy Duty Electrical and Cooling, Nerf Bars, Rhino Liner, Tinted Windows

 

Gears,
I have a 99 4.6 with 1000 miles on it. I drive a mix of city(35%)/hwy(65%).
I have filled the tank 4 times and I am averaging 17 MPG ( 16.5 low - 17.5 high).
I alway use the A/C because of the humidity.


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99 XLT SC, 4.6 L,MacNeil Window Deflectors, Ford-Duraliner Bedliner, K&N Filter, Westin Nerfs.
Family Hauler

 

GEARS -
This question will go on forever and there will never be a correct answer for everyone. I have a '97 with the 4.6 motor. Most of my driving is a combination of city and highway and I get 17.5 MPG consistantly. The lowest number is 16.5 and the high was 19.2 for an all highway trip. My average is definitely 17.5.

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Black '97, SC with 4.6, automatic, 2-4 Belltech drop kit, SnugTop fiberglass lid, billet bumper grill, fog lights, American Racing 17x8 wheels with 275-60 Goodyear Eagle GT II tires.

 

You really can't go wrong with whichever you choose (seems like someone else just said that, is there an echo in here?)

Now that I've said it, let me back up. If you plan to do any towing (or think that you may in the future), go with the 5.4L -- if you do significant towing, get the PSD. I repeatedly test drove both gasoline engines, I talked with a lot of people who owned these V8's, and I listened to what the general concensus of the members of this board was. I decided on the 5.4L as I will likely tow a trailer in the future and I couldn't be happier. If I had gotten the 4.6L, I would probably still be as happy as a pig in slop.

I added the Snug-Top Hi-Liner and that actually increased mileage by ~½ MPG. If I can keep my foot out of the gas (which NEVER happens -- it's just too much fun) I can get close to 17 on the highway. I also just added the K&N filter and I'll keep an eye to see how much improvement that adds.

The only drawback about the 4.6L that seems to come across from most board members is that it is a little light in the power department (if you look at people's signature lines, most power mod's are done to the 4.6L).

--Note to all 4.6L owners, please don't think I'm bashing your engine, I don't want 500 e-mail death threats--

Jim

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'99 F-250 LD 5.4L SC XLT in White/Silver (w/ EVERYTHING 'cept leather and engine block heater) -- added: SnugTop Hi-Liner & carpet kit, Donnelly mirror, K&N filter, more to come... (SuperWhite 9007 bulbs, IAS shocks, and Westin side bars are next)

 

I just purchased a 97 4.6 automatic tran and my first mpg check I got 15.8. This is city driving with the 3.08 gear.

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97 4.6 F150, 88 5.0 Mustang 1/8 = 7.409 @ 93.72 mph

 

OK, just for *****s and giggles.....12 mpg city/highway combo. SD crew cab, 2x4, at, 4.30:1 LS, 6.8L V10

 

With 14,000 miles on the truck now, I get 15.4mpg city / 19.1 highway. This is averaged over the last 5000 miles.
Mileage was significantly less during the first 7000 miles!
Highway mileage drops to 16 average when towing my 2800lb boat.

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'98 F150 XLT S/C 4x4 4.6L 5spd 3.55 Lt Denim Blue, Raven camper shell

 

I have been unable to hit 13 per gallon in a 5.4 4x4, it is a mix of highway and city. but the power is awesome and at $1.80 a gallon for regular unleaded it is tough

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99 F-150 sc, 4x4,5.4,wedgewood blue,mods are on the way