Gas Mileage Concern

[CreativeMind]

So my gas mileage has went down enough to raise a concern. When I bought it I was averaging anywhere from 19 to 21 mpg. Recently its been going as far as 16mpg. I did put new tires on, Duratracs, but it shouldn't have dropped it that much, should it? I just changed the oil and put in a new filter. It dumped some snow for the first time so I switched to 4wd and now im getting 11 or 12. Is there some other reason why the mpg is falling so low?

 

[tick2791]

What size are the tires? If you went from p to lt type tires, it will drop your mpg that much due to weight and rolling resistance

 

[CreativeMind]

265/70/r17

 

[DallasGooner]

Possible issues with the brake calipers? I have read of people noticing a drop in MPG as a sign they had seized calipers.

 

[MikeInNH]

How many tanks have you been averaging 16 now??

New tires certainly could have caused the drop. So could winter driving in general.

 

[iDRiVaT4R]

According to Tire rack, the Load range C tires weigh 44 lbs, and the load E tires weigh 50 lbs. That could decrease your mileage there, along with the beefier tread perhaps. But for comparison, I'm running almost the same tire size, just in a 16" wheel with BFG AT's, my tires weigh 51 lbs each and mine is full time 4x4 V8, I'm averaging 15 mpg overall.

 

[Flyer]

Winter gas has more Ethanol, which usually causes a drop. Also, compare the tire weight to your old tire weight. Going from my stockers up just one size and a slightly higher stance due to the FJ suspension dropped me by two mpg. Still pretty good for a V8 but it did drop from 18.5-21.5 to 17-19.

 

[crackiswack]

How are you calculating the gas mileage? The larger diameter also affects the calculation by ~3%

 

[CNJ Runner]

same thing happened to me bro. I have a 06 v6 sr5, went from 285/50/20 nitto 420s's to 265/70/17 c load duratracs, i get about 16.5 city driving, up to 21 on highways. its normal.. they are LT heavy bigger tires.

 

[Seatown]

Winter gas has more Ethanol, which usually causes a drop. Also, compare the tire weight to your old tire weight. Going from my stockers up just one size and a slightly higher stance due to the FJ suspension dropped me by two mpg. Still pretty good for a V8 but it did drop from 18.5-21.5 to 17-19.

this

 

[Javelin]

I was getting 19 with my 05 V6 stock, but after my mods (lift, tires, rack, Bumpers) Im getting 16.

 

[ronsta]

Ohh.. another MPG thread, I'm in!

 

[SR5 Iron]

Winter gas has more Ethanol, which usually causes a drop. Also, compare the tire weight to your old tire weight. Going from my stockers up just one size and a slightly higher stance due to the FJ suspension dropped me by two mpg. Still pretty good for a V8 but it did drop from 18.5-21.5 to 17-19.

Oh Man, I am gearing up for the FJ mod, but if I loose 2 MPG I might I have to reconsider.

 

[sonerick]

11 or 12 mpgs is a little bit low for the V6, but I guess not entirely unreasonable with LT tires and winter gas blend. I'd definitely check into it though. Look for seized calipers, dirty engine air filter, old spark plugs, dirty throttle body/maf, seized idler/tensioner pulley's, etc. All of these things can drain efficiency and contribute to low mpg's.

For reference, I went from 19.5-21.5 mpg's to 15.5-17.5 mpg's after I installed my lift and tires. I attribute most of the loss in mpg's to the the LT tires, which are much heavier than the ones I had on there before. I also attribute some of the loss in mpg's to the winter gas blend (installed my lift just as stations around here switched over). Hopefully I'll get another 1 mpg or so back in a month or two when it's warm again.

 

[imdav2u]

My gas mileage always drops in the winter.I live in the St. Louis area.I did take a road trip Tuesday.60 miles per hour,no head wind,58 degrees outside,hand calculated,23.7 mpg. I usually get 19 to 20 around town and 10 miles each way to work,about 1 to 2 miles better in the summer.A lot depends on driving habits.If I have a heavier foot,I only get about 17.

 

[ronsta]

Oh Man, I am gearing up for the FJ mod, but if I loose 2 MPG I might I have to reconsider.

would this be due to the truck being raised a couple of inches b/c of the FJ suspension?

 

[Flyer]

would this be due to the truck being raised a couple of inches b/c of the FJ suspension?

I think mine was mainly due to the taller/heavier tires (also grippier tires) and possibly a bit due to the inch higher stance. It takes more energy to spin up heavier tires and gripper tires create more rolling resistance. Still, I would not change anything...the stock suspension has so much body lean that it throws too much weight on one side or the other when having to make a sudden turn or move. It's more like 1.5 mpg lower on the highway. It hasn't hit 2.

I do realize the MPG concern for those using it as a daily driver. I drive my Forester to and from work most days and get 27 mpg, so it doesn't bother me.