Suffer poor MPG???

[Old Jeeper]

Do you suffer poor MPG on the highway vs city?

It may be this: I get better MPG in the city than on the highway and my highway speeds are 64-74 cruise control. Need wondering why city gives me 14s-15s, Hwy drops to the 13s.

Then by accident and I often drive with my hand on the gear shift I move it into Manual on my Automatic and I look at the dash and I am in 6th GEAR and I am at cruise at 72 mph. I am on a trip of about 100 mi in interstate. I discover that I can only go into 7th/8th gear manually, it does not up shift to it.

NOTE: I been playing with this for a week and no matter I have to use manual to get into 7-8 gears.


Anyone else discover this?

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[Twisted Patriot]

I can get my MPG a lot higher in the city than on the highway as well.. but I attribute that to my heavy wheel and tires.. they don't allow me to see 8th gear for sure.. 7th rarely.. if I'm cruising in the city at a steady 30 to 40mph.. I can get over 20mpg.. highway not so much..

 

[yokramer]

Stock 2L I can get 22mpg mixed driving 75mph hwy and 55ish back roads if I really try. Just driving normal Im around 20mpg on the same 50 mile round trip.

The fact youre not getting to 7-8 gear is where your bad mileage is coming from need to figure that out.

 

[roaniecowpony]

I can get my MPG a lot higher in the city than on the highway as well.. but I attribute that to my heavy wheel and tires.. they don't allow me to see 8th gear for sure.. 7th rarely.. if I'm cruising in the city at a steady 30 to 40mph.. I can get over 20mpg.. highway not so much..

It's not the weight. It's the diameter. Otherwise a lighter flywheel would give you better mileage

 

[Byrds8]

If memory serves, weight will indeed cut down your mileage. if you take the same weight/width tire but different diameter, you tune and fix the speedometer and nothing changes. Change the weight and/or width and then its a different ball game. Higher weight makes it work harder to turn. I want to say for each lb of unsprung mass its like 7lbs of static weight. The width just causes more friction which will also increase mileage. Granted, this is what I recall and I could be wrong LOL

 

[yokramer]

If memory serves, weight will indeed cut down your mileage. if you take the same weight/width tire but different diameter, you tune and fix the speedometer and nothing changes. Change the weight and/or width and then its a different ball game. Higher weight makes it work harder to turn. I want to say for each lb of unsprung mass its like 7lbs of static weight. The width just causes more friction which will also increase mileage. Granted, this is what I recall and I could be wrong LOL

Yea any extra weight the engine has to turn will make it work harder causing lower MPG not sure where the idea that weight doesnt matter came from

 

[Ratbert]

@Old Jeeper, your Jeep's computer is aware of your tire diameter and your diff ratios, right?

MPGs decreasing as your speed increases is, of course, expected once aerodynamics come into play.

 

[yokramer]

@Old Jeeper, your Jeep's computer is aware of your tire diameter and your diff ratios, right?

MPGs decreasing as your speed increases is, of course, expected once aerodynamics come into play.

Shouldnt be chilling in 6th gear if its stock. But I dunno what hes done to it so stock may not be the case

 

[aldo98229]

Do you suffer poor MPG on the highway vs city?

It may be this: I get better MPG in the city than on the highway and my highway speeds are 64-74 cruise control. Need wondering why city gives me 14s-15s, Hwy drops to the 13s.

Then by accident and I often drive with my hand on the gear shift I move it into Manual on my Automatic and I look at the dash and I am in 6th GEAR and I am at cruise at 72 mph. I am on a trip of about 100 mi in interstate. I discover that I can only go into 7th/8th gear manually, it does not up shift to it.

NOTE: I been playing with this for a week and no matter I have to use manual to get into 7-8 gears.


Anyone else discover this?

I had this happen when I ran on 35s, Mopar lift, on the stock 3.45 gears. I was getting 13 MPG on the highway as well. The transmission wouldn't shift beyond 5th and 6th gears.

As soon as I re-geared, the transmission started shifting to 7th and 8th gears again. I now get 15 MPG at 75 MPH; 18 MPG if I stay under 70 MPH.

 

[Wabujitsu]

Do you suffer poor MPG on the highway vs city?

It may be this: I get better MPG in the city than on the highway and my highway speeds are 64-74 cruise control. Need wondering why city gives me 14s-15s, Hwy drops to the 13s.

Then by accident and I often drive with my hand on the gear shift I move it into Manual on my Automatic and I look at the dash and I am in 6th GEAR and I am at cruise at 72 mph. I am on a trip of about 100 mi in interstate. I discover that I can only go into 7th/8th gear manually, it does not up shift to it.

NOTE: I been playing with this for a week and no matter I have to use manual to get into 7-8 gears.


Anyone else discover this?

Don, I don’t recall what size tires you’re running. I’m on 35x12.50 mud tires, stock wheels, 2.0T and 8 speed, Rubicon with 4.10 gears. I see 8th from 47-80 MPH, without having to manually shift. The MTs are Falken Wildpeaks.

 

[ForgottenTaco]

90% or more of my daily commute to/from work is back roads and average 21-22mpg. Maybe I drive like a grandma ?‍

 

[west tex]

When I got larger (33") tires 2 years ago, I specifically went for one that was only about 5lbs heavier than the stock 32s that came on the vehicle. My avg mpg over 12K miles has been in the 24-25 range.

I've found that the mpg drops rapidly over 65 mph, so that's where I set the cruise control for highway driving. Also, I tend to featherfoot around town.

 

[3TV]

What is this "gas mileage" thing you all speak of? Should I be checking that?

 

[Staddenmobile]

I drove from Central Oregon clear over to Crescent city CA through the mountains, down 101, then 1, clear to Capitola CA. Then, drove back up I5 to Central Oregon. 1,459 mile trip. (55-75 MPH most the time) 23.5 MPG and around town, 21.5. It’ll catch 7th/8th when I pass 60-65MPH, by itself. 2-door, JL 2.0 T. Performed stellar!

 

[Heimkehr]

If memory serves, weight will indeed cut down your mileage.

That's been my experience when I install the winter wheel/tire combo. Each one is 19 lbs. heavier than the OEM wheel/tire. Ceteris paribus, my average fuel mileage during the Cold Times drops by ~3 mpg. A portion of that reduction likely includes the effect of winter-blend gasoline, also.

That's just the cost of doing business.

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