I just bought a 1998 Ford F150 supercab 4x4 it has the 5.4 and i cant belive it 11 miles to a gallon on the highway.That sucks.It has 50,000 miles i put a new fuel filter and K&N air filter.It has the 355 gears i hope it gets better than this,can some one help?

 

if it doesn't have factory tires you may be getting a false MPG reading. but your MPH would also be off. My '98 5.4 Expy with 3.73 gears gets about 16 on the highway/ 12 city.

 

My 99 S/C has the 5.4 in it. I consitantly {spelling} gets about 15 to 15.5 miles highway.

 

My '99 gets around 14+ highway (and city mixed) and 11 city.

 

I just bought a 98 F-150 supercab lariat with a 5.4L and I got 15MPG on my 1st tank in town, got close to 16MPG on the highway on the 2nd tank.