Wow , some of the MPG's listed are really low , I'm surprised . I have a 95 5.2 4x4 short box reg cab with 180K and a manual trans . It's probably the best on gas I've had with a V8 in some time . 1 tank of pounding the **** out of it in the city and I get just shy of 400 miles , I'm only on my 3rd tank since buying it . I have the same engine in my Grand Cherokee and that thing is lucky to get 12 on 32's , the truck was running the same but now on 33's with no difference . Perhaps the 3.55 ratio and the 5 spd manual have lots to do with it .
Seafoam is great stuff , but , even better is mopar CCC(combustion chamber cleaner) . The application method is easier , simpler and you get to clean the throttle body while doing the treatment . Did I mention it's cheaper too !
If your pinging , it could be the plenum leaking , or , as was my case , a clogging cat . Since hollowing it , I can't get it to ping in 4th gear and doing 20 mph . Before it would play quite the tune with the rockers , lol . I was planning a plenum teardown , but I guess it can wait .

As far as I can tell , I'm getting 17-20 in the city and loving it

 

ya, a manual trans gets better mileage than an auto at least from my exp. i think it has something to do with the fact that you can shift earlier if you wanted to, and you can go into a higher gear at a lower spead, which lowers your rpms, and burns less fuel.

but anyways, im seeing about 13.5mpgs on valvoline synpower, fullsynthetic oil, k&n drop in filter, tonnau(sp?) cover, on a 5500lb ext cab 1500 4x4 5.2 auto.

 

Manual trannys get better fuel mileage because they are more efficient. Less power is lost in the clutch. Autos have a torque converter which is never 100% efficient causing lots of lost power (why lockup torque converters were designed for cruising- to maximize efficiency).
The shift points/RPMs do play a role one way or another, depending on your shifting patterns. Some people shift really early, others at the red line, and this does have some effect on mileage, but you also have to consider # of RPMs vs. rate of acceleration. Slow acceleration is not necessarily more efficient just because of lower RPMs. It takes more time to go the same distance.

 

I get unlimited

 

depends on how im driving
anywhere from 11 to 17
so far i got the biggest boost from the 14x3, gained nearly a mile per gallon if not more, plus it uncorked the 318, and just sounds cool

 

just ran my first tank through the new to me 1999 1500 4x4 with 5.2 in it and i averaged 13.4 with about 60/40 city/hwy that sound about right?

i have no reference on how it is supposed to drive (power and all that) first truck to me it drives great LOL

 

yes lhaskins, thats actually good mpgs...

I have 4.10 gears, New timing chain, New harmonic balancer, New Intake manifold with Hughes plenum kit, New dist.cap/rotor, plugs and MSD 8.5mm wires, new exhaust with hollow cat and i get the following;

City- 11-12mpg
Highway 19-21mpg

and thats with a 4x4 5.9L with alot of extra weight and 208K...i dont hammer on it, i drive it normal, but i dont drive like a granny either....its rare that i get the tach over 3K

 

sweet, thanks for the info.
I just bought it last Thursday. Well i traded my 2002 escape for it and i love it so far.

I have NO idea what has been done or hasn't so I am starting with fresh fluids and air filter. Each check I will do a little more to get everything going great. I am hoping to achieve something close to what you get hwy. but cannot afford to do it all at once. Baby steps haha

 

1998 1500 5.2 3" lift 285/75....i get 15.5 on the highway cruising at 60.

 

2001 3.9L SWB 147K, getting at best when I drive it like a granny 15.5 mixed highway/city