What gas mileage are you guys getting?

Fishtaco said:
My fuel economy went up a bit after I started to change at higher revs as suggested by a few on here which sort of went against my logic but it worked!
Except 1st to 2nd which I have now started a gentle low rev change and the dreaded 6 speed 1st-2nd non mesh has gone I change 1st -2nd at speeds like I would a truck or what ever you call them in US? Actually what do you call a heavy vehicle given everyone seems to call their pickups a Truck? lol

Also my 6 speed is hardly ever in 5th or 6th, I now run it as a 4 speed unless on the highway, last straight 6 cylinder I owned had a 3 on the Tree (Column shift) Ford Falcon, I dont think TJs need all them gears!
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Yeah I've been slowly getting comfy with the idea of keeping it at higher revs. So I shift from 1st to 2nd around 2500-3000 in most cases and don't feel any mesh. I'm also the same as what you said the only time im in 5th gear is when I'm going around 60 on the highway, this puts me around 2100-2200 rpm as a crushing speed.

I do think I could keep my revs higher though in terms of my average revs per tank.

I've only had this jeep for around 2k miles and I've been working from home the whole time. Once I go back to work it's about a 40 mile commute everyday so I'm sure the gas milage will get better then.
 
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Mazepam said:
Yeah I've been slowly getting comfy with the idea of keeping it at higher revs. So I shift from 1st to 2nd around 2500-3000 in most cases and don't feel any mesh. I'm also the same as what you said the only time im in 5th gear is when I'm going around 60 on the highway, this puts me around 2100-2200 rpm as a crushing speed.

I do think I could keep my revs higher though in terms of my average revs per tank.

I've only had this jeep for around 2k miles and I've been working from home the whole time. Once I go back to work it's about a 40 mile commute everyday so I'm sure the gas milage will get better then.
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Often times with shift points, you want to stay where the engine has enough torque to accelerate or maintain speed. Often this occurs at peak torque. Peak torque is a bit high in the RPM range for Jeeps and the Jeep engines aren't quite as powerful as many of us have become accustomed.

In really powerful trucks sometimes it's better to just stay low in the RPMs, since you've got so much more torque than you need, you can just drive around barely touching the accelerator and get ok fuel economy. In not so powerful trucks it seems that running more gearing and higher RPMs tend to help MPG. I'd never had a vehicle that I had to shift on the highway until the Jeep TJ. My first highway trip I kept it in 5th gear (AX-15 with 3.07s and 33s) and I could see the fuel gauge drop trying to maintain speed. I filled up before the highway and used several gallons to go 50 miles. Basically if you don't have enough torque to do what you're trying to do then your MPG is gonna be very poor. You can get more torque by engine

Later I had to do some driving for work and just play around, I would mostly keep it in 5th, but just lightly touch the gas pedal and though I couldn't maintain much more than 55 mph typically, I was able to average 18 mpg with that same setup multiple times. If my RPMs really dropped, I would have to do some shifting, but I maintained fairly low RPMs. I never got to try it the other way, because my plan was to do a diesel swap and I never regeared or tried to do the same with higher RPMs. Plus I switched to some really aggressive mud tires and the MPG just fell off the map with those and the tires would shake the Jeep over 55 mph, so I didn't do a lot of testing, but my MPG were like 11.

I do run a bit higher RPM now with the Jeep and have swapped around tires and gotten really good MPG, but I have not been able to isolate any single factors, but I know I have to use a lot less pedal when I'm towing if my shifts are higher in the RPM range.
 
I feel like to maintain good torque i would need to be between 3k-4k at all times while accelerating on the highway, (like going ONTO the highway) because i know if i get higher into 3rd and def in 4th my acceleration potential goes way down when its between 2k-2.5K.

Now what I've do is that ill keep it in 4th until i know I'm at a cruising pace so the RPM are at around 2500-2700 and then ill put it in into 5th gear and this keeps the rpm around 2k, If i lightly touch the throttle or put my foot all the way down it will still accelerate at the sale rate so my foot is always slightly on the pedal and it maintains speed.

The only time i got into 6th gear is if I'm on highways around me like 287 and 78 here in Jersey and im maintaining around 70 mph on flat ground or on a decline, if there is even the slightest incline 6th is useless with the 31st i have now.

Keep in mind this is my first manual transmission car ever so I'm learning as i go what feels good.
 
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Mazepam said:
I feel like to maintain good torque i would need to be between 3k-4k at all times while accelerating on the highway, (like going ONTO the highway) because i know if i get higher into 3rd and def in 4th my acceleration potential goes way down when its between 2k-2.5K.

Now what I've do is that ill keep it in 4th until i know I'm at a cruising pace so the RPM are at around 2500-2700 and then ill put it in into 5th gear and this keeps the rpm around 2k, If i lightly touch the throttle or put my foot all the way down it will still accelerate at the sale rate so my foot is always slightly on the pedal and it maintains speed.

The only time i got into 6th gear is if I'm on highways around me like 287 and 78 here in Jersey and im maintaining around 70 mph on flat ground or on a decline, if there is even the slightest incline 6th is useless with the 31st i have now.

Keep in mind this is my first manual transmission car ever so I'm learning as i go what feels good.
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What's the gear ratio of your axles? I've always been annoyed that Jeeps had 3.07s offered with the AX-15.

For me and the 4.0 and the AX-15, 5th gear was useless, but I was so used to manuals where you could go into the higher gear and do anything you needed, that it was a big learning curve for me and I'm still figuring it out. The wind resistance plays a part too. At slower speeds 5th could be used a little.

Even with the 306ish ft lbs at 1,800 RPMs, 5th gear, 33s and 3.07s still aren't quite what you want on the locally hilly terrain with a rack on the Jeep. To be honest, I should have probably gone to 4.10s, but I went with 3.73s, which is a great compliment to my setup. I will be swapping to a smaller A/T during the summer months when I'm towing more and don't need 33" mud tires.
 
Mine is 3.73 for the 6 speed I have. I figured when i go to 33's in a few months i should be fine because as you said I have a manually i can always just put it in a lower gear to get around.
 
Mazepam said:
Mine is 3.73 for the 6 speed I have. I figured when i go to 33's in a few months i should be fine because as you said I have a manually i can always just put it in a lower gear to get around.
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I would suggest you eventually regear to 4.56. You will be much happier if so.
 
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If I had the 4.0, I'd be running 4.56s. I probably should have gone 4.10s with 33s and the R2.8, however I typically think of going to smaller tires rather than large ones. Most of where I'm at 33s and skid plates are great. I could go to 35s and still be ok with 3.73s, but I'd be less happy.

However when towing I don't really like the large tires, but that's likely due to the tread than anything else, but during boating season, there's benefits to dropping down the tire size and being a bit closer to the ground when towing through these really twisted and really hilly roads. Plus the braking of the Jeep is less than stellar. Smaller, lighter wheels/tires stop a bit easier. However I probably should have gone up in rim size and gone with bigger brakes, because I'm not gonna add trailer brakes for our tiny fishing setups.
 
DieselJeep said:
If I had the 4.0, I'd be running 4.56s. I probably should have gone 4.10s with 33s and the R2.8, however I typically think of going to smaller tires rather than large ones. Most of where I'm at 33s and skid plates are great. I could go to 35s and still be ok with 3.73s, but I'd be less happy.

However when towing I don't really like the large tires, but that's likely due to the tread than anything else, but during boating season, there's benefits to dropping down the tire size and being a bit closer to the ground when towing through these really twisted and really hilly roads. Plus the braking of the Jeep is less than stellar. Smaller, lighter wheels/tires stop a bit easier. However I probably should have gone up in rim size and gone with bigger brakes, because I'm not gonna add trailer brakes for our tiny fishing setups.
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Yeah it seems like using the tire chart 4.11 is what's in the sweet spot for 33's, how much does your gas milage really change though? I feel like if you can choose the gear and your not jamming the accelerator it wont change much, however youll have to push the throttle harder with bigger tires so i might just be talking in circles.

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Mazepam said:
Yeah it seems like using the tire chart 4.11 is what's in the sweet spot for 33's, how much does your gas milage really change though? I feel like if you can choose the gear and your not jamming the accelerator it wont change much, however youll have to push the throttle harder with bigger tires so i might just be talking in circles.

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IMO it's less about the fuel economy and it's just having a bit more response with the pedal and not losing much MPG. Also for getting the crawl speed down a bit too. The stock Jeep is fine for easy trails, but WAY too fast doing anything that makes you nervous.

However a guy at work didn't like it with his bigger tires and gear ratio. He was having to do a lot of shifting around town, but I think he just felt weird on the highway with the engine just screaming.

But I've never had a setup where I was doing 4 or 5 shifts avoiding the rev limiter just to get to like 45 mph or something. Actually I guess I have, but when you're doing work or something where you're pulling you really don't care about a lot of shifting as long as you've got plenty of torque.
 
My 05 6-speed was getting 14-16 with 3.73s and 32” (tape measured) tires.
Same tires and 4.56s I’m getting 14. It is much better to drive after the re-gear.
Most of my driving when I calculate mileage is my 24 mile each way work commute. It’s 65-70 in the morning with the cruise set for 3/4 of it and 55-70 on the way home with a little bit of traffic.
Any 4wheeling and it drops, but I consider that normal.
My rpm at 70 is 2750ish and 75 is about 3k.
 
Claytone said:
My 05 6-speed was getting 14-16 with 3.73s and 32” (tape measured) tires.
Same tires and 4.56s I’m getting 14. It is much better to drive after the re-gear.
Most of my driving when I calculate mileage is my 24 mile each way work commute. It’s 65-70 in the morning with the cruise set for 3/4 of it and 55-70 on the way home with a little bit of traffic.
Any 4wheeling and it drops, but I consider that normal.
My rpm at 70 is 2750ish and 75 is about 3k.
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Yeah i would imagine correcting for the 10% or so difference in the speedometer at highways speeds I'm most likely getting 14-16 like you mentioned as well.

However i am going to start commuting to work again and my commute almost exactly like your is listed just a few more miles.
 
When my soft top half doors TJ was the 2.5L, 3-speed transmission, 3.73 gears and 31x10.5s it got 15.5mph religiously...

Anxiously awaiting to see what it gets now with all the changes...
 
I can’t believe this thread came back. If I wanted good gas mileage I would have bought a Prius.

And 33’s with 3.73 gears and the 6-speed is going to suck after awhile.
 
JMT said:
I can’t believe this thread came back. If I wanted good gas mileage I would have bought a Prius.

And 33’s with 3.73 gears and the 6-speed is going to suck after awhile.
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Not sure anyone is chasing Prius gas mileage more they want to know what others are getting! If my gas mileage is way lower than others then I want to chase the cause. my tj is a toy so I don't care how low my gas mileage is as long as its comparable to others and I can make it to the next gas station. :)
 
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Fishtaco said:
Not sure anyone is chasing Prius gas mileage more they want to know what others are getting! If my gas mileage is way lower than others then I want to chase the cause. my tj is a toy so I don't care how low my gas mileage is as long as its comparable to others and I can make it to the next gas station. :)
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I think this thread has adequately proved that anything between 11-15mpg is quite normal. No one needed to strike up the band again just to hear the same noise.
 
The better question might be what MPG do you get when you're off-road on trails. A Prius would get much worse MPG, once it got stuck 5 ft onto the trail.

Jeeps aren't inherently bad MPG, just the wrong engines were used. I feel like high RPMs = more broken stuff off-road, so I just don't think the torque curve is a good fit for the application and especially the factory gearing. That being said the bad choices probably had more to do with regulations and how MPG and emissions were determined by the Gov, which don't have bearing in real life.
 
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