Is 15.8 MPG about right?

[Bolt snapper]

I know I'm pushing the "Annoying New Member" envelope with all of my inane questions, so I apologize in advance. I promise I will let up here shortly once I do a thorough shake out and get a few issues resolved.

As you may know from my other recent posts, I've recently purchased an '04 5.4, and one of the issues I have right off the bat is fouled up front brakes. I'm in the midst of throwing parts at that problem to try to fix it. In the mean time, I took the truck on a 250 mile road trip last Sunday, and according to the odometer reading, the highest average MPG is 15.8. I don't have a heavy foot, don't accelerate hard (in fact, kind of baby a vehicle). Average speed was probably 65 MPH. 15.8 MPG was the highest the display hit. Is this typical for this year, motor, etc? I'm trying to gauge whether or not the slightly sticky brakes are robbing mpg and/or if any other issues exist (clogged cats, etc). I tried a search for "mpg", but it must be too few characters, and I couldn't find anything. Nothing in the stickies either.

Let me know if this highway mpg is low and I need to find a contributing issue! Thanks!

 

[ManUpOrShutUp]

The '04 was rated at 15/19 new and mileage inevitably drops with age, so I don't think 15.8 is bad at all.

 

[Habbibie]

15.8 is in my opinion on the high end of what most second gens gets so keep driving like a grandma bro

 

[Gary Waugh]

I usually average 13.9 with my Gen 3 expedition, so i think you are doing very well to get 15.8!! There is not much wrong with your engine or you have a very light foot!!

Gary

 

[ManUpOrShutUp]

I usually average 13.9 with my Gen 3 expedition, so i think you are doing very well to get 15.8!! There is not much wrong with your engine or you have a very light foot!!

Gary

The techs at the dealership told me 13s is what they usually see on the 3rd gens when they come in for service. I was running 15.8/15.9 (and am atm also) and he told me that was excellent. Eek! That helped me go in with low expectations from the start.

 

[DanTheMan97]

I wish I got that good of gas mileage in mine, to be fair though I do a lot of towing though. I've gotten anywhere from about 8mpg up to maybe 13 at best. Definitely not the most fuel efficient vehicles around

 

[Bain64]

I'm at 13.1 when 100% in town driving, but i used to get mid 14's before my fuel pump regulator decided 89 psi was just fine.

 

[JExpedition07]

If your getting anything over 1 MPG your good, get a nice cruiser (boat) with twins. Now we are talking gallons per mile!!!!!!

 

[Habbibie]

I wish I got that good of gas mileage in mine, to be fair though I do a lot of towing though. I've gotten anywhere from about 8mpg up to maybe 13 at best. Definitely not the most fuel efficient vehicles around

I'm sure a Prius can tow something... you sound like a person who should be driving a Prius or a Chevy....

 

[BillAlex]

I have two Gen Two's both 2005 and both two wheel drive. I have noticed that when I am at highway cruising speed I set the Cruise Control and I run right at 17 MPG. When I leave the Highway, it drops of course. 14 or 15 not unusual for city traffic. Also, I have over 215,000 miles on my main driver (I am rebuilding and restoring the latest one) and I bought it new. I used Mobil 1 Synthetic from the day I drained the break in oil to currently. I have been known to drain the oil at 3,000 miles and dump what appears to be Cyrstal clear brand new oil. I am a believer that these engines (5.4L 3V) are meant to go 300,000 miles and then some if taken care of. If you walk away with one thing, remember this. Change the Oil Religiously and you will be rewarded with longevity and great gas mileage.

 

[Matticus]

15.8 actually seems kind of low to me. I had an 03 5.4 for about 5 years (just sold it a few months ago) and we would drive between Salt Lake and Pocatello on a monthly basis. Cruise set at just over 75mph and, unless there was some sort of crazy head wind, we would average about 16.5 on the low end when the weather was really cold and ~18 when it was mild. A few times I set the cruise at 70 instead of 75 and I'd get 18.5-19. If I'd set the cruise as low as 65, I'll bet I would have got close to 20. The vehicle had 162,000 miles when I bought it and 215,000 miles on it when I sold it. The gas mileage never varied from what I described as the miles went higher. So, it may be an indication of something that needs attention, or possibly just a difference in vehicle wear and/or where you were driving

 

[blue oval guy]

i get approx 16-17 tops with my 4x4 5.4L, 15.8 is absolutely normal, maintain proper tire pressures and make sure have clean air filter and plugs, obviously those small things matter to eke out an extra mpg or 2. good luck and nice choice in truck!

 

[Bruce Mitchell]

My '99 EB 5.4 AWD/4WD is running at 14.8 MPG, virtually all highway driving. 250K miles. LOF service every 3K-ish miles.

 

[ltharley]

We have a high milage 04 EB with the 5.4 and we get about the same mileage at those speeds.

 

[JERRY DOOLITTLE]

So my Expedition is a 2002 XLT AWD with the 5.4 liter engine, and 198k miles. 16 mpg is what I get on average. Of course that drops when I'm out in the woods and 4x4 is engaged. Not sure how bad it gets tho.

 

[Matticus]

Interesting reports. It's not like a mpg or 2 is going to be life changing, but I'm surprised others are reporting similar numbers. I must have had a real gem of an Expedition.
Just an FYI, I would manually check the mileage against what the vehicle display was reporting every so often to make sure it was correct. They were always within +/- .5 mpg of each other.