It's all been said. My 4.6 has 190,000, and I've pulled
24-25mpg highway several days this summer(200-300miles per day)
mixed with slow country road driving.
Usually, the average highway is around 20. Was much worse
before I got new tires. 5.4 in Expedition is putting out 11.5mpg according
to on board readout, mostly city driving. Needs new tires badly.

 

The 4.6 will always out last the 5.4 if both are treated equally because the 4.6 has a shorter stroke. Less movment equals less wear.
With that said I would probably want a 5.4 over a 4.6. I like power

 

If you guys would, please list your gear ratio with your mileages. My '95 5.0L 4R70W 3.31 getting 12 MPG is on it's way out the door. I'm going to find a '97 - '03 so I'm really paying attention to these MPG post in your forum.
Thanks!

 

I have a '98 F-150 4x4 SC w/4.6. I mostly just drive it, but occasionally hook onto a trailer. I was getting about 19mpg on the hwy before I put 33" tires on. Now it's more like 17, but still seems to be able to pull what I need with 3.55's in the rear end. I'm sure it works a little harder than the 5.4, but I have 118k and not a thing wrong.

 

I know quite a few ppl that have the 4.6 and If they even got 15 with them that was great to get even that good. 20 mpg and higher!!! Are you guys actually penciling down the figures to figure it out or just reading the electric readout cause those things aren't very accurate in my expierence.My dad's lincoln with the 4.6 only gets like 22 to 25 and he drives really nice.

 

I calculated it out on two different tanks of fuel, and both were just over 22 miles to the gallon. I checked my mileage with a gps, and my math isnt that bad, plus I double checked with a few different guys, just to make sure I did it right! Keep in mind that is pure highway driving too!

 

No, my figures are not "penciled in." I make it a practice to maximize fuel economy in ANY vehicle that I'm driving, and some very simple, free to all steps can make a big difference in overall fuel economy of a vehicle.

I have a high tank of 31.4 mpg out of my '98 Jeep Cherokee 4x4, with the 4.0 inline 6 engine, and 5 speed manual tranny.

I logged a high tank of 57.9 mpg out of a 2003 Toyota Prius I used to own.

I logged a high of 40.0 mpg out of a '06 Ford Escape Hybrid I owned briefly.

I logged a high tank of 14.8 mpg out of my 37 foot diesel pusher RV on my last trip in it.

I have a high tank so far of 37.1 mpg out of my new Chevy Aveo, and that car's engine is still breaking in.

The 98 Police Interceptor that I just got rid of logged a high tank of 27.7 mpg.

I keep to a maximum of 55 mph, and take advantage of every single opportunity possible to coast. I avoid driving during traffic rush since I work shift work. I plan my routes to cover all of my errands in one trip, making a loop out of the list, getting the farthest stop done first. It's all about driving with a deliberate goal towards max fuel mileage.

 

All depends on what you plan to use it for and what your idea of "better" is. Nothing wrong with the 4.6. I have an '02 4X2 X-cab with the 5.4. and 3.55's. Best highway MPG ever was 21, a 1 time good deal. I average between 16-18.5 in mixed driving, (70% highway, 30% city). I drive with MPG in mind. Before I bought mine I drove a 4.6 regular cab 4x2 and was impressed with it. The MPG difference between the 4.6 and 5.4 seem insignificant to me. I went with the 5.4 because I tow cars occasionally and wanted the extra torque. I'm kind of concerned by the 5.4 spark plug issue though.

 

It does make you wonder when the heads for the 4.6 and 5.4 are the same.

-Kerry

 

Test drive one of each.....on the highway.
The answer will be clear almost immediately.
I know it was for me before I bought mine.

 

My 97 F150 4.6 4x4 auto w/3.55 gears has gotten me on combined milage of 15-17mpg. On the highway if I set cruise at 65mph I can get 18+mpg. Those numbers are w/ 188000miles on the truck.

I'm happy w/ the 4.6 because I very seldom haul or tow anything. I've towed a 5000# trailer in the city, and the 4.6 has plenty of power to pull.

 

97 F150 4.6 liter with M5OD and 3.55 gears gets 16-18 mixed driving.

 

98 kcab 5.4 w/3.73 gears gets 20 mpg on my last trip. Checked with GPS. I try to keep RPM's below 2k. Mods incl flowmasters, airaid, and 295.75.16's.

 

Guess I'll chime-in too. '01 shortbed, single cab, 4x4 offroad, 5.4L, stock-size BFG All-terrain tires, 3.55 gears, Advance Cover folding tonneau cover.
City: 15 mpg - normal driving
16 mpg - while keeping engine rpms under 2K

Highway: 16 mpg - before tonneau
17 mpg - after tonneau and usually doing 75mph.


A friend of mine has a 2000 2wd extended cab with the 4.6 (not sure what gears). I don't know what gas mileage he gets, but that 4.6 sure sounds like it's straining under normal acceleration compared to my 5.4.

 

I sure appreciate the MPG/engine size/ratio reports. I'll probably try for a 5.4L but won't be disappointed if I end up with a 4.6L. The 3.55 ratio seems to be the best for mileage when keeping with the stock tire size or at least close. I have a buyer for my '95 so it looks like I'll be "movin' on up" to the '97-'03 model and board real soon. Thanks again!!!