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I Just Drove To Birmingham, Al This Weekend From Destin. About 480 Mile Round Trip. We Went Through A Number Of Small Towns So It Was Not All Interstate Driving. I Would Say 60/40. When On The Interstate, We Averaged About 80 Mph. I Reset My Computer Ampg At The Beginning Of The Trip And When We Got Home, It Read: 17.6 Mpg. I Was Suprised. Just To Show The 5.4l Is Not A Super Gas Hog.
Imagine that.... the 5.4 really isn't a gas hog! If you check with other people you meet you will find that the new 3 valve motor gets much better mileage than the old ones. The truck I traded in on my 04 was a 97 Expedition. It had a 5.4 with 3.73's. I also had Flowmaster exhaust, a K&N FIPK, and a Hypertech chip. It had 185,000 on it when I traded and I was getting abot 16 on the highway. Before any mods I was lucky to get 13 on the highway.
P.S.... just don't let Sean find out.... he'll call you a liar!
I get 16-17 on a 2000 5.4L with only 2 mods - Air force one intake and duals from the muffler back. Using 5w20 gave me a 1-1.5mpg increase. I still can't afford to drive it much though. I knew a guy that was getting 20mpg in his 5.4L 3 valve.. I wonder what his secret was.
just did my first highway trip with my 2005 4wd screw lariat 9000 miles only changes are a K&N drop in filter and a SIDO magnaflow cat back and 93 octane gas no tuner yet waiting on mine but got 17.3mpg I get consitant 15.5 to 16.3 driving to work thru northern ma souther nh up an down hills country roads only other thing I have is a Tonneau cover. I have seen a lot of controversy over these giving better mpg but mine does no brag just a mathematical fact