I have a 98 f-150 ext. cab auto 3.55 have 285/75/16 and on my last trip I got 20.5 mpg running 67 to 72 mph with the a/c on and off depending on the temp. I have several mods and now at 203 rwhp. dan

 

I have 4.2L manual with 3.08 and get 17-18 in city consistantly with the superchip, Airaid, and flowmaster. Over 31K miles and still getting good mileage.
On the other hand, the Expy with the 4.6 sucks it down.

 

nice basset hound chipper lol
I have one too, lovable little dogs!

I get about 15 all the time

 

Thanks Patrick,
I have more pics of them with my truck in my gallery. The link is in my sig.
Any pics of yours? I love those damn dogs.

 

I bought a '01 F150 Xl, sport flareside in Feburary of this year. It got 16.1 on the first tank and slowly crept up to 20.5 after about 5000 miles.

Have 17,500 on it now, and it's still running about 19.5-20.5 with %80 hwy driving everyday.

A month or so ago, I ran a couple of tanks of premium through it and performance was significantly improved.

Plans are to chip it, install FloPro exhaust, and K & N filter.

Bill

 

wshppp,

You wrote, "A month or so ago, I ran a couple of tanks of premium through it and performance was significantly improved"

I doubt very seriously that this is the case except via the "butt dyno", which just loves to discover power improvements... I have one, too.

Premium gas actually has less BTU's per gallon than regular. The reason? Since lead has been banned as an octane enhancer, MTBE is used... yup, exactly the same stuff as in oxygenated fuels... only in lesser quantities as an octane booster... about 1 cup per gallon.

Premium gas offers no benefits unless you are experiencing pre detonation. You will get less mpg with premium than with regular because of the lower energy content. Premium gas does not burn "slower", it takes a higher temperature to cause it to burn, which is why it stops pre detonation. Actually, the MTBE causes a delay in the breakdown of the long chain hydrocarbon molecules (hexane, heptane) into the short chains that actually are oxidized.

It used to be that premium gas contained an additive package that did a better job of keeping injectors and carbs clean, but the EPA has mandated that such additive packages must be present in all fuel grade levels to assist in controlling pollution.

If you put the chip into your truck you will need to run premium fuel since the chip will advance your timing, increasing cylinder head temps, and hence the likelihood of pre detonation. I would also note that the increased cylinder head temps will cause an increase in the output of oxides of nitrogen (N02, N03). This is why the timing is retarded in the first place... to control these pollutants. If you live in a state that does tail pipe checks for this pollutants, you might check with the chip manufacturer to insure that you can continue to pass inspection.

For more information on octane, try:

http://www.f6rider.com/VRCC/tech/octane101.htm

 

I get 16-18 around town with mine. The best i done on a trip was 24.

 

well i finally got some numbers in ....normally getting between 13 and 15 mpg....but then again i have a v6 with 33 inch tires....and like the others with the chip, air force one, and exhaust i love to push my car to its limit....

 

My average is 16-18, it's never been on an out of town trip yet so we'll see.

Red

 

My very first road trip, right after I got my truck (had about 35K miles on it) I got right at 20mpg. This was on a very cold day, no A/C, and about 95% highway speeds. Shortly after that, I had the muffler/tailpipe TSB done that rerouted the pipe to behind the right rear wheel instead of in front of it. It is only a coincidence that since that time I have never gotten better than about 16 mpg even on road trips?

 

I just took a trip to Laughlin, Nevada, and was following pops on the way there. I got 21 mpg's there. On the way home was a different story, I got 11 mpg's coming home. Because it is uphill(at least a lot of the way) coming home, I was almost always in 4th gear with my manual tranny. Oh yea I have 3.08 on my 4.2L. Average I get 14mpg. I don't know how you guys do it with your 3.55 gears. I guess because I drive it like a car.

 

My 99 F150 Standard Cab shortbed Auto 4.2v6 with 3.55 got 15mpg on a 1200 mile trip at 78mph pretty much the whole trip. I pulled a travel trailer with it and got 9mpg. I now have a 5.4 supercab and get about the same except when pulling the travel trailer its gets alot better then 9mpg.

 

I've been getting 13.5 in the city and about 17.5 on the highway (@ 80 mph). The worst I've seen was 12.4 from a tank of premium gas, all city driving. The best I've seen was 19.5 @ 80 on the highway. I drive like I stole it, so I don't expect the best milage. Either way, it's better than the lifted Bronco I used to daily drive (10 mpg).

Mitch

 

I average 17 mpg in mixed city/hwy driving. I've gotten as low as 15.5 in the middle of the winter & 20 mpg highway on a vacation trip. I was expecting a little better mileage from a V-6 since I'm not a leadfoot, but I love my truck anyway.

 

I don't know how thick the mud is you guys are driving through but my 2000 4.2l reg. cab 5speed gets a consistant 23-24mph and I live at 7000 feet!!!!!!!!!