You should definitely see improvement once you get several thousand miles on it. City driving is going to restrain your numbers for sure though.

 

I'll bet it is discouraging! How did you arrive at that 14.5 mpg figure? Mine was certainly much better than that when new--around 18.5 mpg (calculated by me, not that brain dead computer). That was mostly around town driving. But, is your "around town" more like NYC (red light every hundred yards), or OKC (red light every half mile or mile)?

 

I'm getting about 18 average in mostly stop and go driving. I like this engine. This is nearly as good as my 93YJ 4 cyl. I love the 3.8 and find it to be refined, and with plenty of power. The only complaints I have are with an issue with the MyGig and uploading CDs. Other than that, I'm very pleased with it.

 

I've got an 08 Sahara with a 6 spd (i'm still learning to drive it so i rev it high a lot) and just broke 300 miles. I've been getting about 18 mpg in city traffic and it is getting better. I can't imagine how anyone is getting less than 17mpg without some serious alterations or heavy foot driving.

 

I have noticed a significant increase in the power of this engine with 3000 miles on it. I find it a good match for the purpose of this vehicle, not too low on power and not too much power.
I have had it feel sluggish at times, but the problem there is computer related ( A totally different thread) not the engine being too weak. I also get the impression that in this world of 300+ h.p. engines that people are let down when they don't have something that will get them from 0-60 in 4.6 sec.
I guess I just look at what I have. I have a Jeep. It can drive on the highway just fine, I'm not racing anyone. It can ride the trails and get you through a lot,......even stock like mine ( I'm just too lazy for the crazy stuff )
Look at the original Jeeps, 4 cylinder engines and you know they didn't have 300 h.p., just a well balanced package with the engine, transmission and gearing for what they were intended for. You have to think of what you have, what do you use it for ( out accelerating the guy next to you? probably not gonna happen, but I bet my arse you can go places they only dream of. Great gas mileage,........ it's shaped like a box.)
I get 16-19 mpg, all depends on highway or city driving. It also depends on my right foot, unfortunatly it doesn't always weigh the same. Give your Jeep a few thousand miles, you might change your mind on the power and mileage issue.
I think I'll go out to the garage and get me a beer now.

 

No offense, but as an automotive engineer, you should be well aware of the mulitude of compromises that take place when bringing a product (especially such a complicated project as a vehicle, much less an off-road, road safe, convertible with all the latest electronic doohickeys), to market.

This guy I work with won't put anything aftermarket on his vehicle because he firmly believes that the automotive engineers know best and designed the vehicle right the first time (again, not a slam on you or on automotive engineers in general). What he doesn't understand, and what many people who aren't engineers (and sadly, many engineers) don't understand, is that there are many requirements of a design. Design can obviously be strength, size, or weight, but also has to be cost, longevity, environment, ease of manufacture, availability, reparability, and more. It's never as easy as opening up your Roark's Formulas for Stress and Strain and picking which design you want.

Every part on a vehicle has to be design with all these and more requirments tugging the final design in many directions. My friend doesn't see that I can upgrade something to a higher level than the factory did, just by paying a little more, for example.

 

Just put a Flowmaster Super 44 Offroad muffler and a Jet Stage I performance chip in this week. Noticed an immediate difference with the chip. Made the engine much more responsive and sounds less sputerry. The Flowmaster sounds great and tucked up nicely behind the back bumper. Haven't gone through a full tank of gas yet but I hoping to go from an average of 11 mpg to around 13-14 and I'll be happy. Adding a cold air dam intake should add even more oomph!

 

Well I went trail riding with an 06 TJ yesterday and it seemed like his engine had so much more torque than mine. I am definitely ordering a cai this week and a throttle body spacer. As far as my gas mileage goes I have a heavy foot and I get 13 or 14 mpg which sucks cause my chevy 1500 got 15 mpg with a heavy foot. I am disappointed with this motor and I will be the first to buy a diesel if they come here!!

 

I actually test drove a 4 door diesel prior to buying the petrol. It was $4000 more than the petrol and at the time I figured a 3.8 v6 would be ample (I like the sound of a petrol), I have to admit that maybe I picked the wrong engine, the diesel pulled hard from low revs with very little lag from the turbo and cruised really nice at 110 kph. Don't get me wrong, I love driving the jeep with the 3.8 but sometimes wish it had more torque lower down, feels more like a 2.8 4 cylinder sometimes. I wonder how much of that is down to the computer, I can be moving along in 2nd sometimes with the revs around 2000, boot it and nothing happens as though the computer is "thinking" about wether to give you the ponies, it picks up then starts to do it's thing but there's always that delay as though the software is responding to the input from your right foot and trying to calm down your request. Switching off the ESP doesn't change anything. What does everyone else think??