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Whats your YJ's MPG???

11K views 35 replies 31 participants last post by  BlackSmoker 
#1 ·
I am looking to buy a YJ w/ the 4.0L and I have heard a wide variance in average MPG from people. So you all help me out and settle this. If you could post your year, average mpg to date, and current mileage that would be awesome. I do plan on modifying the YJ so those number count too.
 
#4 ·
My crawler, 37" tires, 4:10 gears, T-18 and a 258 gets 12ish. You are about to make a big mistake if you are going to buy a jeep and hope it gets good gas mileage. Anything modified will most likely see less then 15mpg. Only stockers as a whole get anything higher, even the highests ive seen i 20 mpg or so with the right setup and highway driving.
 
#8 ·
around 14 if I stay out of the boost

around 8 when im in the boost

1993 stock 4.0 turbocharged running 5.5 pounds of boost, ax-15, 5.38's, 36" tires for street driving, 40" maxxis CC's for the trails
 
#12 · (Edited)
Nope

Honest to god 21mpg on the HWY over varied terrain (couple east coast mts). Did that for multiple tanks over the whole trip. The mileage was measured on a 2004 Toyota Corolla that I was following. I had them keep track of the mileage because my fuel gauge doesn't work and I don't trust the odometer. The tires were Dunlop Rover Ats. They are really shitty tires, but they are light and apparently have low rolling resistance.

79 CJ5 with stock 258, MC2100 1.08 46 jets, 9.5 pv, GM HEI
T150/D20 D30/AMC20 Stock gears (probably 3.37 or so)
Doing a slow and steady 55 mph.
21 mpg no kidding.

Probably doesn't do that anymore after some mods. Fuel is also shit now a days.
________
COLORADO MEDICAL MARIJUANA
 
#13 · (Edited)
i was able to get 16 or so when i had my rig on 33s. But i never drove faster than 55 on the freeway. Jeeps are square, not good for fuel economy. My jeep is also a hardtop. With the top off mileage drops a bit. But then again i have a 4.2L and not a 4.0 last owner changed some stuff in the motor so it has more torque.
 
#15 · (Edited)
More spec's than you'd need in my sig , but I basically concur , 15ish MPG reguardless of driving style .

I try to even out the average by putting as many miles as I can on my sportbike , scull-crushing acceleration @ 46 MPG :)
 
#19 ·
'89 4.2 with electric fan, ax-15, dana 44's, 4.88's, and 37" mt/r's right at 13.5 mpg.
 
#24 · (Edited)
94 YJ 4.0 ax15 Dana 44 front, 9 inch rear 4.10 gears 35" procomp tires. I get 16 MPG around town. I've yet to run a full tank on the highway with this set up but I drove about half a tank on the highway and the other half around town and when I filled up and calculated the MPG was 21, so my highway mileage is over 21. I think the locking hubs really help out my highway mileage
 
#26 ·
91 4.0HO, Auto 4speed, 3.95's, 35x12.5's Always mixed terrain more low gears than highway.

Now, with the cracked header and hardtop/full doors 12.58mpg
Before with good header, softop and 1/2doors 14mpg.
 
#27 ·
Thanks for all your posts on this subject. I am not buying a YJ strictly on economy. I was just curious, started asking around and got a huge range on answers. basically same thing i got from all of you. If you leave it stock and don't hot rod it you can get 20-22 mpg. but with modifications and trail use the mpg's start decreasing. I plan on getting a YJ, and put a set of 30x9.50's on then calling it a day. Till I can afford to shorten the tubes on my f/r 60's and stuff my mopar 408 stroker motor in it. Then the mpg's will be around 8. I will definitely be posting that build. again thanks for all the responses
 
#35 ·
Yeah man, I was in the same boat as you... kinda... I have and drove a 1969 GTO as an everyday driver then i bought my 94 YJ with a 6cyl for gas milage and I am getting better than 22 mpg on the highway. I plan on puttin 31x10.5's under it in the next month or two and I dont expect much of any drop in mpg's
 
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