There are definitely pros to doing this. I've gotten over 24mpgs in 2 different jeeps. My current driver gets 27+ regularly. But this is with no lack in modification.
28" tires
3.55s
All boltons in a jeep that weighs under 2700#s.
But none the less it's possible.

If everything is right, cruising at speed on the highway (50-60mph) I can see economy in the 29-31mpgs.

Just saying there is improvements to be made, they are just small, and have to be added up to get anything substantial

 

That's city speed man…see what you get between 75 and 85.

 

What your neon injectors are compatible?

 

It's still in the 25-28 range once I'm moving. It'll still do 25ish at 100-110mph. The issue is launching stop and go, I can drop clear to 4-8mpgs. Big difference between babying it and run what ya brung

 

Sometimes I think it is just gearing too. My XJ can't handle 75 mph in West Texas (it's flat enough, but generally too windy) in overdrive. Get into any hills and you're just better off running in 3rd gear. I took it from Lubbock to Fort Worth and averaged around 13 MPG. Gets a little hilly.

My Trailblazer can't hand any of the Central Texas pulls running 80 in OD. Haven't gotten it on a 85 yet, it might handle 85. Making the same run to Fort Worth, it'll pull around 18 MPG.

 

Still can't believe people install those "cold" air intakes, pretty much been proven they are bull$hit.

 

Did the 703 injector swap 3 years ago, if there's a milage gain it's not much, maybe 1/2mpg. However it's does idle much smoother and the throttle response is better.

I have a hard time believing anybody gets 25mpg from a 4.0l in a vehicle with terrible aerodynamics. I have a honda accord with a dramatically more advanced 4 cylinder engine and superior aerodynamics that averages about 30mpg. I can only assume the speedometer is way off there by throwing off the calculations, or the math itself is flawed.

I have averaged 17-18 mpg for the 4 years I've owned the jeep. I don't accelerate hard not do I drive over 65mph.

I even tried hypermiling aka (driving like an a$$hole and breaking many laws in an effort to keep the vehicle in motion there by increasing fuel economy) and still only improved to 20-21.

The reality is you're simply not going to get good milage in a 4wd jeep.

 

Agree with this completely. What size tires are you running getting 17-18mpg? I am running 31" tires with 4" lift and am light on the throttle - averaging 13.5mpg city 16 mpg highway. I'll take it, but would be great to get a few more mpgs. The injector upgrade seems like a good choice either way.

 

il just throw this in there. i had a vacuum leak. unaware. just found it one day. fixed it and went from 13.6mpg to 14.3

 

I'm on 31's with a manual tranny and 3.07's

If I hot rod a bit I drop 3-5 mpg, the key is smooth acceleration and not speeding.

I can't remember the exact figure, it was in an article I read somewhere, but I believe it require almost 15% more fuel to drive 65 vs 55 in a pickup truck.

 

Well thanks for doing anything but directly calling me a liar.

As I stated I don't have a "typical" jeep. So yes, my numbers are a best case scenario, but that doesn't mean they're impossible.

I believe that the biggest difference comes from my tires. I very between a 27-28.5 tall tire in the back, and run a 25ish 5" wide tire up front at about 55 psi. With very light wheels, and when I'm doing any sort of trip, I normally air the rears up to 30-40 psi.

As far as gearing, I'm still running factory 355s, which means with the converter locked in OD it'll just putt along at 1000-2000 rpm.

With regards to aero, I still have all my factory aero, bumper end caps, flares, and no roof rack. I also make sure my tires stay inside my fender flares. Which is a major cause of drag. My jeep also has a rake to it, which I can't see hurting it. Also the lowest fuel I run is 93, normally with some sort of additive.

 

Pic to give ya idea. Currently working on getting new pics with it lower.

 

Have you verified the accuracy of your speedo? Most aren't very accurate.

My is closer to being spot on AFTER I switched to the larger 31" tires than it was on the stockers.

My speedo was off by 10% on stock tires, @65mph I was actually doing 60. GPS verified.

 

My "Speedo" is GPS. I run a Bluetooth obd integrated gauge setup that uses GPS for speed...The key is engine efficiency. I'm making way more power so I don't need to use as much of it, so it's easier on the setup. Everything I'm the bay is heat coated or heat wrapped. Along with parasitic drag is lower with no a.c. compressor, a much shorter belt, and mechanical fan delete. Like I said it's all the little things that add up. Also I tend to drive using hyperbole techniques, gain some speed for hills, never use the brakes, etc. Because driving has a ton to do with it, when I go out with some buddies and pick on people at red lights, I might get 6mpgs

 

Depends on more than what was just tested. All they really tested are what is known as stage 1 intakes.

There really isn't much point in a stage 1 kit.

Stage 2 kits don't usually perform as well as they can. Why? Most vehicles sporting multi point fuel injection or direct injection have this little thing called a mass air flow sensor. Let me explain MAF logic…not getting a lot of air, lean out the fuel supply or getting more air, make it richer. Very few modern engines lack MAF sensors and very few CAI owners retune their computers to get the MAF to compensate for the extra air.

The big question. Why do most XJ owners go with a CAI or snorkel? Look at the location of the factory air box…right behind the driver's head light. What usually gets wet first on little plunges (or Lubbock style flooding)? The factory air box is also fairly poor in design with that 90º bend…como sé dicé turbulent flow?

I saw an average of 3 mpg increase (from 16 to 19) on my daily driver when I installed a Stage II kit. Not much more throttle response or even noticeable from the seat of the pants dyno. One thing to remember, my dd doesn't have a MAF sensor.