I just finished a long, 3,000 mile trip from Colorado to Pigeon Forge, Tennessee and back, and have to say I am pleased with how well my '03 F150 XL 5.4L 4X4 w/3.55LS performed. This trip started last Saturday morning, with my return last night, 4 days on the road. I bought this truck in April, started the trip with 8800 miles on it.

The trip down I got an average of 15.95 mpg, running at 70mph. I picked up a 12 foot trailer in Tennessee with about a 1500 lb. load. Return mileage dropped to 11.33 mpg. I would guess my average speed with the trailer at 65 mph or so. Not as bad as I had expected after reading some of the horror stories of towing mileage wth the 5.4.

I must say the performance overall was outstanding, and my comfort level was quite good. I knew the trailer was there, but I had no problem maintaining the speed limit and only occasionally would it drop out of OD.

Now, to go change the oil again.......

 

Have you ever tried towing at slower speeds?
I'm just curious how fast the 5.4 likes to run with a load on it.

 

Dave,

I did tow for many miles at various speeds, just went with the flow and speed limits. I kinda missed on my original post as to the load I was towing. It was a 12 ft. tandem axle closed trailer, and I had about a 1500 lb. load inside. I would guess the trailer weight at around 800 lbs or so.

As for towing speeds, I felt the 5.4 was comfortable at most any speed below 75. I had good acceleration if I need to pass, and did run up to around 80 once without a problem. That is other than the trailer didn't like it! I wold have to say the best speed was probably around 65. Pulled the hills quite well at that speed, with a minimum of dropping out of OD. I did run about 150 miles wiht the OD off. I didn't do that on purpose though. I had switched it off while in some good hills and for got to turn it back on. Mileage for that leg was about 2mpg lower.

The truck loved being at lower elevations (real air)! I noticed that as I got closer to Colorado it was a bit more sluggish, but that is to be expected. I can't say for sure right now, but I did run on some lower octane gas and think I felt a difference. I am going to go back through all my receipts and see if I can find a noticable difference in the mileage.

Anyway, hope that answers some of your question.