MPG going downhill???

[BattleCatRoots]

So i swear when i first got my truck at 43000 miles it would say i had 360 miles to go each time i filled my tank. then i noticed it started to go down very slowly, and now at 53000 miles im only getting 313 per full tank, but it still says im getting exactly 16.0 mpg and that's never changed! what gives? i havent done anything to my truck that would have caused this (at least not yet - getting it lifted with new bigger tires soon). its a 2004 sport edition.

 

[MikeInNH]

First off...STOP using the computer to tell you what your gas mileage is. They are notoriously inaccurate.

When was the last time you changed the plugs??? Air filter???

This time of year my gas mileage drops also. Winter gas and just driving in the snow is the biggest factor.

 

[BattleCatRoots]

I had no idea the computer was inaccurate, ive been going entirely off of that! Had a tune up recently by my favorite mechanic in the world who i call lthe toyota whisperer, so im pretty sure im all good in that department. ill do a real test and see if im actually getting a low mpg but now that you told me that i doubt theree is any problem with it thanks!

 

[Dexter Morgan]

Check your tire pressures as well, this can have an impact.

 

[Brazenhead]

Register at Fuelly | Share and Compare Your MPG

This by far will be the most accurate. Your first fuel up will not show your mileage as it is starting a base point. Just remember when at a gas station and the nozzle clicks, do not try to "top up" your tank. This will give you inaccurate reading. Also if your at half a tank and you fill up, do not enter it as a partial fill. Partial fills will not give you an account of your mpg's.

I'm averaging 14mpgs during these winter months.

 

[JDSupreme]

Although the computer is inaccurate, I still like to use it as a reference. First off, after you fill up, you have to go in and reset the mpg. The miles til empty setting does it automatically, but it is calculated by whatever your last average mpg reading was. I figure it gives you approx 1-1.5mpg better than what you are actually getting. I usually hang around 17.5-17.8 on the screen and when I do the math im in the high 16's.

And the only time I don't have the computer set on "blank", is when I cycle through after fill-ups to reset and make sure there isn't a significant drop.

In regards to tire pressure, after I got new tires I noticed a drop in mpgs. They were at around 31psi and taking them up to 33psi gave me about 1.5mpg better. Such a small thing can make such a difference!!

 

[MikeInNH]

I figure it gives you approx 1-1.5mpg better than what you are actually getting

You may find that YOURS might be closer to being accurate then others. This type of system is NOT designed to be accurate. When I first got the truck I did careful calculations of my mileage (actually I still do) and compared them to the trip meter. It varied widely from week to week. Sometimes it was off by 1mhg...others weeks it was off by 9mpg. I stopped using it as a reference.