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Discussion Starter #1
I am planning a 2.5" Daystar Level for the front only on my 08 FJ.

Maybe a dumb question, but one that needs to be asked...Does leveling/lifting affect the MPG for the FJ?
 

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The answer is Yes
It affects mileage because you are allowing more air flow under the truck, which equals drag. If you notice the stock FJ has a Rake to the front end. Even though it doesn't look as good as level, the design helps mileage. It may not be a drastic change, but it will affect it.
 

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The answer is Yes
It affects mileage because you are allowing more air flow under the truck, which equals drag. If you notice the stock FJ has a Rake to the front end. Even though it doesn't look as good as level, the design helps mileage. It may not be a drastic change, but it will affect it.
+1

In addition, most folks folks put on larger tires that weigh more than stock after a lift, and the unsprung weight of heavier tires is really hard on fuel economy because you continually have to spin that extra weight every time you touch the gas pedal.
 

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Another YES from me. Any mod which adds weight or changes aerodynamics will decrease mileage even if only slightly: heavy skids, heavy tires, steel wheels, heavy bumpers/winch/extra battery, aftermarket rack, lift kit, hi-lift jack, all the extra crap you carry in the back.

If you've already installed off-road tires and encountered the loss of mileage that comes with them you may not notice the additional decrease in mileage.

Although I still wish that I could get better mileage, I do feel somewhat fortunate that, even with all of my mods, I am able to average 16-17 mpg with careful driving on my interstate only trips back and forth to Colorado/Utah.
 

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with lift and tires, if you keep it under 70MPH your mileage will be OK hit 75 or 80 and it's bad............. I really don't care, love the FJ, but it is noticable
 

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Discussion Starter #8
Not planning on a lot of mods. I am getting 19.5 mpg right now with roof rack only. I am adding OEM rock rails (more weight) and will be doing the front level lift. My tires are new and I don't plan on replacing them till needed. At that time, I will probably stick with same size, but more aggressive treat. I had Toyo ATs on my last truck and on my Ranger and I like them.
 

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I'm with DoWork on this, I agree with the theory, but in practice I noticed no difference. (I only calculate my mpg to the tenth though) The only change I made was a lift/level and my mpg has been identical. The more aggressive tires will make a big difference, even in a stock size however. I lost around 1.5 mpg by going from the stock tires to a mud terrain in the same size.
 

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+1

In addition, most folks folks put on larger tires that weigh more than stock after a lift, and the unsprung weight of heavier tires is really hard on fuel economy because you continually have to spin that extra weight every time you touch the gas pedal.
I don't think it's the weight of the tire so much as it is the rolling resistance of larger tires plus the effect on gearing. Larger tire means lower gear ratio. I found that out on my 5 speed manual 2500HD Silverado crew cab. A few pounds in tire weight meant nothing to a 6500 pound truck. It was the extra circumference and rolling resitance that affected the mileage by loading the engine slightly more than the stock tire.

Also. the first thing I did after going to the larger tires was getting the front end alignment checked to make sure the change didn't affect the alignment.

And of course tire pressure is added to the equation, I almost always run near the max pressure marked on the sidewalls.
 

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The unsprung weight can be a factor. However, as with your example, you are less likely to notice an extra 100 lbs of unsprung weight on 6500 pound truck.

You are right too that the unsprung weight increase is typically encountered when putting on bigger tires . . . wider tires will add rolling resistance and taller tires will add load to your engine/drivetrain. I too would guess that the rolling resistance and extra load of taller tires will affect mileage more than the unsprung weight increase.
 

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:bandit:Wow James, I thought you drove faster than 60mph
Another YES from me. Any mod which adds weight or changes aerodynamics will decrease mileage even if only slightly: heavy skids, heavy tires, steel wheels, heavy bumpers/winch/extra battery, aftermarket rack, lift kit, hi-lift jack, all the extra crap you carry in the back.

If you've already installed off-road tires and encountered the loss of mileage that comes with them you may not notice the additional decrease in mileage.

Although I still wish that I could get better mileage, I do feel somewhat fortunate that, even with all of my mods, I am able to average 16-17 mpg with careful driving on my interstate only trips back and forth to Colorado/Utah.
 

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I averaged around 18mpg mixed before installing my Toytec lift and almost 2 years later my average is down around 15mpg. I can only contribute the loss to the lift because nothing else has changed. I also wonder if the inability to get the alignment back into spec can cause some rolling resistance issues which can also hinder mileage and acceleration.

Seriously considering dropping mine back down to get my smooth riding FJ back.
 
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