I have a 1989 Ford F-150, I love it. But what I am worried about is Milage. I have the C6 3 speed automatic/ no overdrive. What kind of mileage am I gonna see city/hwy?

Here are some other specs of my truck

Engine: Legendary 4.9L 300 Inline 6
Trans: C6 3-speed auto/no overdrive
2WD
3.73 Gear Ratio Rear Axle
Miles: I am unsure if it has rolled over, this truck has been in other hands of my family, and it reads in the 98000's, but I am unsure if thats 98000, 198000, or more...

The only modification I have made, was removal of the muffler, and used the existing 2 1/4 inch pipe to make a straight pipe system I left the catalytic converters in place, and I made a turn down in front of the axle. The only real difference is sound, i think it gave a bit of power, but it seems to not want to keep a steady idle now...

 

I had an 87 with a straight 6 and 4 speed (manual) which averaged 15-17 mpg on the highway. In town was closer to 10-12 mpg.

I really liked that truck! It was a Supercab with a short bed.

 

I just sold an 86 F250 with 5.7L gas and 3.73 gears 4x4 and 3 speed auto. That was heavier, more engine and 4x4 losses over yours, but it gave 13mpg highway unloaded, and 10mpg towing 3500 pounds with stuff in the bed too. I suspect if the trans was 4 speed (with much lower enginer rpm at highway) the highway mpg would have been farther in the teens. Hope this data point helps.

 

I have an 89 F150 king cab 2wd 300 6 cylinder with fuel injection and 5 speed. It is pretty high geared and presently gets 16 mpg average. It has some issues right now that need fixing but when it was running well it was getting 19 mpg average.