Plastic air dam
JK Super Freak
Joined: Jul 2009
Posts: 1,457
Likes: 2
From: B.F.E, MI
That is quite a difference in gas mileage! From previous threads I thought it might make 1 mpg difference or so when I tossed mine. Never noticed any change in my gas hogs mpg though.
Possibly your new lift and 35" made most of the difference?
Possibly your new lift and 35" made most of the difference?
JK Freak
Joined: Sep 2012
Posts: 526
Likes: 1
From: Auburn Hills, MI
Are you basing this off what the computer says, or have you logged and done the math?
If this was noticed at the same time as the 35's were added, and you haven't re-geared, that would give you a noticable drop; add to that if you haven't reprogrammed the computer for the new tire size, then that could also contribute, and throw off the computers MPG calculations as well (which is why I was curious as to what you were basing it on).
JK Freak
Joined: Jan 2010
Posts: 644
Likes: 1
From: Concord, CA
I was thinking the same thing - seems like an awfully big drop; after market bumper and no air dam on my wifes jeep, did not notice any significant mpg loss.
Are you basing this off what the computer says, or have you logged and done the math?
If this was noticed at the same time as the 35's were added, and you haven't re-geared, that would give you a noticable drop; add to that if you haven't reprogrammed the computer for the new tire size, then that could also contribute, and throw off the computers MPG calculations as well (which is why I was curious as to what you were basing it on).
Are you basing this off what the computer says, or have you logged and done the math?
If this was noticed at the same time as the 35's were added, and you haven't re-geared, that would give you a noticable drop; add to that if you haven't reprogrammed the computer for the new tire size, then that could also contribute, and throw off the computers MPG calculations as well (which is why I was curious as to what you were basing it on).
I have had mine off for a while and can't really tell the difference in MPG's. What usually effects my MPG most is top-down hwy miles and how close to the floor my right foot is...
Thread Starter
JK Enthusiast
Joined: May 2012
Posts: 366
Likes: 0
From: cleveland
I was thinking the same thing - seems like an awfully big drop; after market bumper and no air dam on my wifes jeep, did not notice any significant mpg loss.
Are you basing this off what the computer says, or have you logged and done the math?
If this was noticed at the same time as the 35's were added, and you haven't re-geared, that would give you a noticable drop; add to that if you haven't reprogrammed the computer for the new tire size, then that could also contribute, and throw off the computers MPG calculations as well (which is why I was curious as to what you were basing it on).
JK Super Freak
Joined: Apr 2012
Posts: 1,208
Likes: 0
From: Pittsburgh, PA
My MPG dropped by 1-2 when I took mine off, I also put on a TF Leveling Kit which raised the front 2" though. Still running the stock wheels and tires and average 16 city 18 highway. It'll be even worse once the Toyo MT's go on, ouch! I used to run mid grade gas but tested it against low grade and had the same readings. So now I stick to low grade gas just as long as its from a quality vendor.
JK Super Freak
Joined: Apr 2009
Posts: 1,331
Likes: 0
From: Dallas, TX
Mine was off when I installed front midwidth bumper and leveling kit and I dropped from 16mpg in city to 14.6ish. I never installed the front skid plate it came with until about a month ago. I've since run three tanks and mpg came up to 15.5~15.7. No other changes. This is all calculated by hand. FYI, my computer read out is always with in .2 mpg.
The front skids and plastic do something for the airflow, IMO.
The front skids and plastic do something for the airflow, IMO.
