I normally average 17 mpg with a mix of light city traffic and 65-70mph HWY. The other day I filled up my XJ and drove to a nearby town at some 55mph, some 65-70 and mostly 75-80mph. Once there I drove around for around 20 minutes in light slow traffic, turned around and returned home. I immediately stopped at the same gas station, same pump and filled up. The average for the trip was 18.8mpg. I expected to get lower mileage due to the high speed but I was wrong. Is the 4.0 more efficient at high speeds?
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Better mileage at higher speeds?
- Thread starter xjman96
- Start date
It's not the slower/faster speeds, it's the stop and go, repeated accel/decel. Take a look at any EPA mileage rating and note the City MPG is lower than the Highway.
I just finished a round trip from SoCal to Vegas and got about 21 mpg averaging 75mph.
I just finished a round trip from SoCal to Vegas and got about 21 mpg averaging 75mph.
Crabapple
NAXJA Forum User
- Location
- Greensboro, North Carolina
X2, But above 65 you arn't going to get any better economy. You're mileage will start dropping off severly trying to push your flying brick through the air and of course the lower your geared the worse it's going to be.
Blaine B.
NAXJA Forum User
- Location
- Northwest Indiana
I seem to get in the 12-14 range regardless of what sort of driving I do. Highway OR stoplight every half mile or so type driving. You're lucky.
Around town I get 15ish. Most of my trips are 3 miles or less. I sometimes don't even get up to full temp.
As far as luck goes, I've done quite a bit of work on the beast. I have replaced the exhaust from the manifold back, changed nearly every sensor, replaced most of the cooling system, and fixed a ton of leaks. I also swapped out for Ford injectors and run a K&N in the stock air box. It'd *BETTER* run well.
Next is to tighten up my suspension. <sigh>
As far as luck goes, I've done quite a bit of work on the beast. I have replaced the exhaust from the manifold back, changed nearly every sensor, replaced most of the cooling system, and fixed a ton of leaks. I also swapped out for Ford injectors and run a K&N in the stock air box. It'd *BETTER* run well.
Next is to tighten up my suspension. <sigh>
Hello i have a 92 4.0 5sp 160,000 with 3.07 gears and 235/70/r15 most of my driving is in town getting around 13 mpg have a set of 3.73 gears wonder if it would help any verry little interstate driving .Most of the time hwy is under 60 mph. In 5th running about 1500 rpms . would it be any benefitt to change them besides a little more power. checked and would be running 2600 at 60 with 3.73
CharlesS
NAXJA Forum User
- Location
- Quezon Province, Philippines
My '98 4.0L 5 spd with 4.56s at 98K miles gets 13-14 mpg at 60-65mph and less in the city.
Recently had a custom exhaust system installed along with a free flowing catalytic converter and muffler.
Also purchased new front hub unit bearings online from RockAuto replaced them a couple days ago....
This week I am going on vacation with the wife driving from San Diego, CA to Yellowstone National Park in Montana then over to Mount Rushmore in South Dakota and home...
Will try to drive 65 mph to see if the above changes affect my gas mileage.
Recently had a custom exhaust system installed along with a free flowing catalytic converter and muffler.
Also purchased new front hub unit bearings online from RockAuto replaced them a couple days ago....
This week I am going on vacation with the wife driving from San Diego, CA to Yellowstone National Park in Montana then over to Mount Rushmore in South Dakota and home...
Will try to drive 65 mph to see if the above changes affect my gas mileage.
- Location
- In the islands
I have found that speeds between 55 and 75 have very little difference in MPG's. Dirving against a head wind, stop and go traffic and RPM's above 3,000 do cut into my milage in a big way. I hate city traffic and any place that would not allow the AW4 to shift into 4th gear OD and stay there.
A full tank of gas, about 500 pounds of luguage, 30" tires and 3.55 gears with the cruise set to 70 MPH is a gas drinker on those long hills. I think 4.10 gears are a little short with 30" tires for highway driving. The XJ run up those hills without breathing hard now that I am using 4.10 gears.
A full tank of gas, about 500 pounds of luguage, 30" tires and 3.55 gears with the cruise set to 70 MPH is a gas drinker on those long hills. I think 4.10 gears are a little short with 30" tires for highway driving. The XJ run up those hills without breathing hard now that I am using 4.10 gears.
CharlesS
NAXJA Forum User
- Location
- Quezon Province, Philippines
Having a 5 spd with 4.56s and 32's driving more than 70 mph has me turning above 3000 rpms....; which is one of the reasons why my gas mileage is low...
While my Jeep is setup for rock crawling...; it loves the open road too!!!
It is difficult to stay below 70 mph.
In theory, I'm sure there is but it depends on other factors as well. Tire pressure, composition, and thread pattern affect it too. Loaded weight, winds and terrain/road surface play a role. I can't imagine them playing too large a role in slower speed, city driving. When I load up the family and use my car top carrier, my mileage always drops 1 or 2 mpg.
