I have a 2010 SCAB, 18" factory wheels/tires with a 5.4L engine.
I made a 323 mile, all interstate trip yesterday. Avg speed using cruise was 74 MPH. I used my A/C during the last 1/3 of the trip.
Computer showed 18.4. It was 18.5 before I turned on the A/C.
I filled up this morning, driving only 1 block of city driving and the manual calculation was 16.2. This is terrible in my opinion. My old 98 Chevy with a 5.7 would pull numbers over 18 and it had over 130K on it.
I think I will make a trip to the dealer when I return. The truck should have better numbers being most of the terrain was flat.

 

You complain about 16MPG, I shut my mouth when my truck got back into double digits.

 

WOW, 16.2 is great going 74 in our trucks. You must have had a good tail wind. Congrats! And, definitely don't trust the MPG computer, Mine's off too, but it sounds like mine's a little closer than yours. In my 2009 FX4 going 74, I will be lucky to have the computer show 15.5... Doing the calculation at refill time, I will come out around 15. Now, set your cruise at 65 and you will get MUCH better mileage. If it doesn't drive you nuts being the slowest vehicle for miles. I can hit 19 going 65 (cruise control ON) with a strong tail wind. LOL

My folks have a 1995 Suburban that gets better mileage too.

 

First off, they (mpg meters) are referred to as "lie-o-meters". How much power did your chebby make? How sturdy was that frame? It's like people who compare 1991 civics that got 40+ mpg to todays civics 34 mpg. People always want more power and ammenities, but somethings got to give.

 

You mean I can't have my cake and eat it to? Being sarcastic, 15MPG isn't shabby considering it is a 6,000lb truck. Sure some would like more, yet no two trucks are the same even though they could have the same options and everything. It is what it is man. You want better MPG a bicycle or moped?

 

I'd be in heaven with those numbers! My 08 screw gets 11.9mpg

 

You should want more out of your truck. 12 years to develop better MPG, 3 valve engine etc should do better than a 98 model. My Chevy had plenty of power and did everything I wanted it to. Granted it had it's fair share of intake mainfold leaks and other problems but c'mon man....... F150 should get better than it does.

 

I don't know too many Chevy K1500 that could pull 18mpg with the 5.7 but definitely the 5.3 got great mileage and for whatever reason my experience has been that historically Chevys got better mileage than Ford. Don't know why, but they did. I had 94 and 97 Chevy extended cabs with 5.7 usually around 16-17 mpg haven't seen those numbers since going to Fords. But I also have been driving a much heavier SuperCrews since 2001 that I've put oversized tires on and that isn't a recipe for good mileage!

 

You have to do your calculations over a few tanks to be accurate.

 

I got 19.2 on the highway with my XLT, prior to 10% ethanol and my mods. That was driving 75 -80. I now get about 16. I lost over a mpg with the ethanol, and my big wheels and tires and some other weight additions account for the remaining loss. My 2002 5.3 Silverado Ext Cab was a lot lighter and did not get any better mpg.

 

Yea....you can't forget what that damn ethanol is doing to our mileage. It's not good.

 

Don't complain about 16 to 18 mpg. I have owned fords since i was 16 granted they have all been lifted i see 10 to 15 mpg. my 2010 screw 4x4 averages 16 going 65mph on the highway. and about 12 in the city. your numbers are pretty good

 

I've used Shell 87 octane (E10) gas at every fill-up since I purchsed my '11 5.0L STX SCab.

I topped off my tank this morning with the following results:

3,614.7 total odo miles
225.6 miles on trip A/B (around 70% highway/30% city driving)
11.695 Gallons serviced
19.6 on avg. computer
19.290 mpg, old school math

I find that my avg. comp. is within .4-.6 mpg with conservative driving. As much as 1.6 mpg differential when I drive aggressively.

 

This was one of the reasons why I dumped my 5.4L 3V engine. My display was usually right on the money, and it was always horrible - hovering around 14 at best. One thing to make sure of is that you MUST reset the fuel mileage parameter at EACH fill-up. Mine was never wrong when I checked it at each fill up.

 

That 98 model only made 255 horsepower and had a 6500lb tow rating. Your F-150 makes 310hp and can tow 10K+ lbs. I'd say that's quite an improvement. Remember, trucks have gotten a lot heavier due to gov't regulations and "who can tow most" battles. It's very easy to see why the chebbie achieved better mileage. The truck wasn't built as stout, made WAY less power and was lighter. I'm also curious on which rear end you had in the GM vs. now and tire size. The GM's are know to have little pizza cutter tires on their trucks because their brakes were so small. They had 15" wheels until recently. the Ford couldn't fit anything under 16" because the brakes were so large.