Hello all,
The truck in question is a 1997 5.4L 4x4. I've been getting 14-15 mpgs for ever in mixed city/highway driving. This week, we took a trip from DFW to Galveston and I was eager to see what a few tanks at 70 on cruise control would do. As you can see in the picture, nothing to get excited about!
I bought the truck in March with 110k. Since then, I've changed the plugs and oil, but the truck runs like a dream, so I haven't done anything else. Torsion bars were cranked when I got it, but it appears stock otherwise. I'm planning Gotts and exhaust, and when the geolanders wear out, some A/T tires, but no larger than stock.
The long winded question at the end of the story is- shouldn't I get a little bump in mileage for several tanks at a reasonable highway speed?
I'll be changing the air filter soon ( don't know how old the current one is) and the brakes squeak, so I'll probably do the bearings then.

 

15 mpg for a 5.4l 4x4 sounds about right... gotts mod, a new filter, and an exhaust should help out. but it's a truck and like most 4x4 pick ups, it isn't going to get great gas mileage

 

I'm not looking for great (I wouldn't kick it out of bed for eating crackers ) but I thought it was weird that I get such consistent mileage, no matter the conditions?

 

well you did say you average 14-15 city/highway so that is hard to compare to purely highway. it mainly consists of driving habits but it is somewhat strange that purely highway wasn't at least 1-2mpg more then mixed

 

All depends on wind resistance also. 1 time driving to Cali which was like 250 miles 1 way I got worse gas mileage all interstate then I did in the city because of the wind.

I say if you averaging 15mpg your doing good. Ya, you woulda thought maybe 16 maybe 17mpg if you were on cruise control for long period of time. What were your rpms? When I had stock tires I usually ran 69mph which was like 1850rpm, and 71mph was about 1950rpm, if I went over 2k rpms my mileage dropped.

 

RPMs were right at 2k the whole time we were on the highway. There were also some extended 50 to 55 mph runs on the highway that runs from Galveston to Surfside. There are stoplights, but we had good luck with them. The breeze off of the Gulf was not bad, and was a cross wind anyway.

 

that seems a little strange cause i get about 15.5 mixed and on my last highway trip i got 17 and a good part of that i was going 80