Hello everyone..... i own a 2003 4runner, I feel my gas mileage is very low. i bought a new air filter and still doesnt go up 15.4 mpg.. Does anyone have any clue what could be wrong??? is v6 engine

How do u drive and in what conditions?
Also is your truck stock?
I have had mpg that low stock in lv w ac running all the time.

Reset the ecu.

Other than the air filter, what other maintnance have you done?

I also have a v6 and average about 17.5 mpg (calculated) for mixed driving.

i do like 80% to 90% city driving and i get around 16.2
also keep track of my fill ups.
t4r (Toyota 4Runner) | Fuelly

Winter gas, poor road conditions, cold air and many other factors can decrease mileage during the winter.

Wouldn't cold air help improve mileage based on increased air density and more oxygen per given volume of air? More power with cooler temperatures and less power with higher temperatures.

excess brake dust? May be a frozen caliper dragging you down.

There is a different gas mix in the winter. I definitely notice a 1-2 MPG drop in the winter.

When is the last time you did a tune up on your runner?

I get the same mpg all year long 20-22. Sure winter gas sucks but in the summer I use my AC.

I agree with you that you will get worse mileage in the winter for the reason you point out and for other reasons previously mentioned. My point was that cold air is not the culprit of the loss in milage.

Yea cold air has nothing to do with it.^^^I always understood that cold air is more dense and combusts more efficiently and in theory should give you better mpg.

I think it relates to driving habits, quality of gas you put in your truck, tires, and maintenance.

if you are runnin a big heavy at tire and a lift you wont see 20mpg.

Winter is always bad for mileage especially if you do short trips. A cold engine is not efficient, the gear boxes are more difficult to turn do the the heavy lubricants. Even tires have more rolling resistance.

You might want to borrow or invest in a ScangaugeII

ScangaugeII

Great tool to get a feel for what impacts your gas mileage.... For me (2003 V8) I've learned that its:

Engine temperature - Before being fully warmed up my mileage is typically under 10mpg.... After warm up it's closer to 20mpg... For my normal commute (35 miles) it averages out to around 18mpg...

Speed - I used to drive over 70mph pretty regular.... The scangauge pretty much cured me of that.... Gas mileage is much worst once I hit 70+....

Acceleration - Strong acceleration from a dead stop usually is in the 4-6mpg range.... Once I get to speed it returns to the normal range....

HCF - I took mine out based on some of the posts I read and saw a .5mpg improvement.... Quick and easy gain....

Hope this helps.....

FWIW, I'll be driving from warm Miami to Seattle on Saturday and passing through Denver and into Nevada. I'll also be keeping a close record of the fuel economy as well as the temps we see while on the trip. Seeing as to how I have a stock v6 right now it should give a decent idea as to how much all this really affects the vehicle as well as elevation changes.

Sounds like a great road trip !