It also depends on 2wd vs 4wd. The 5.2 gets better milage than the 5.9

 

It's an old saying I have heard all my life and that is a long while!
Just another way of saying something is real cool or neat or "it don't get any better".

 

The 5.2 gets maybe .75 mpgs better than the 5.9. Its really not much better.

removing the tailgate is a weight savings measure that can certainly help. Dropping it does nothing unless you have a long bed. The air doesn't really become a resistance factor until about 45 mph. But at that speed the air is going over the bed.

Long bed is a different beast. That last foot the air comes down and smacks the closed tailgate. That is why I purchased a soft tonneau cover. Gained me about 1-1.5 mpgs.

Another thing folks dont think about is the gas tank. I have a 35 gallon track on my long bed. Gas weighs 6.073 lbs/gallon. If I only fill up to 15 gallons I save myself 121.5 lbs of weight.

Also, clear all the crap out of your truck that you dont need. If you're brave you can roll without a spare tire for even more savings.

Lifts and big meats on a truck cost fuel too.

if you can sniff 20 mpgs on the highway you are doing really well.

 

My 96 does pretty good. Going to work and back I get 14-17. 25 miles each way. On trips I have gotten as good as 21 at 65 MPH and 15 at 80 MPH. I really can't complain about that.

 

That is pretty good charlie, are you all stock?

 

My 98 5.2 gets about 13/17 on good days. I have also seen 11/15 when my plenum was shot.

 

I have recorded similar results, I averaged 21-23 mpg from Homestead to Keywest. 130 miles non stop at 55mph. At 70mph I am around 19mpg, if I go over 73mph my mileage dips down to 15.5.

 

my averages that ive calculated in the past...

Last summer around the city i would have a consistant average of about 13-14

On the highway its a different story....

I can go to Maine, (284 miles one way) at 68 mph (set the CC) and it takes just a tab bit less then a half of a tank...

So at 26 gallons, half of that is 13...13/284= 21.846 mpg....

and mine has 208K and i have the 360...have a truck toolbox FILLED with tools...still have tailgate up...10 ply tires at 55psi each....I still get that milage.

But this spring my city mpgs have taken a fall....i get around 11 now....and i just replace my timing chain, harmonic balancer, hollowed the cat, and put a muffler on it....and my mpgs went down...

But my highway milag is still up...

I did a 125 mile round trip a few weeks back, and used 1/4 tank....

so 1/4 of 26 is 6.5 gallons.......6.5/125= 19.230 .......that was going with Cruise at 72 Mph.....


i just dont see why its such a difference with highway and city....but i live in the REAL city...alot of stop and go so that can play a huge factor...


but all in all my stats as of right now are about this

City- 11 mpg
Highway- 20 mpg

thats pretty good for a 4x4 5.9L with 208K, and the bed filled with tools.



sorry to ramble...thought id give my stats

 

No internal changes.Just catco low restriction cat and flow master American thunder duals at the time. Now have a Fram boost CAI but the only difference I have seen is better throttle response and the old unsilenced air filter sound under hard acceleration.
Also 3.55 rear with 265 70x16 tires on 10" wide wheels.

 

using the AC hurts your gas mileage. Your engine has to work harder once the compressor is activated. So it takes extra power to run the AC. Not running AC gives you better gas mileage. About 1-2 MPG. ANd 1MPG is close to 10% in our trucks...that is a big bump.

Here is the gas mileage thing explained from my 2001 that gives a display of your average and also REAL TIME MPG economy.

My 2001 5.9 with my mods:
MILES PER HOUR:
85 MPH: 11.8 mpg cruising
70 MPH: 13.1 MPG
60 MPH: 15.2 MPG

BIG DIFFERENCE HUH!!! The faster you drive, the more your MPG plummets.

Here is another test from 2 weeks ago when I moved:
Towing and hauling 3,300 lbs of stuff traveling 65 MPH
In OD: 10.6 MPG for 15 miles (relatively flat)
Out of OD: 12.9 MPG for 15 miles (relatively flat)
In OD until I hit a hill, then took it off OD to stay at 65 MPH for 15 miles : 11.1 MPG average, instant MPG readout

Reason for that is because being in OD bogs your engine when hauling ANYTHING. You will need to push down on the gas pedal to keep a constant 65 MPH whenever you get to an incline, and it will bog going up a hill then kick out of OD.

You get better gas mileage when you are towing and it is NOT in OD.

--Dan