MPG on computer wrong

[SalsaRed4Runner]

Hello All,

Just wanted to run this by you all. Myfirst 2 fill ups on my 2006 6cyl 4 Runner have been 21 gallons. I'm getting roughly 410 miles out of a tank. That equates to around 19.5 MPG. Pretty good right? I'm happy with that...

However, the onboard computer states that I should be getting around 20.5 MPG. Actually, it hasn't dropped below 20.5 at all on this last tank. Yet I'm computing 19.5...

Is this supposed to be 100% accurate or is it just a friendly reminder of how you are burning fuel?

Wondering if anyone else is seeing the same thing...

Again happy as a pig in $hi^ with 19.5.... =)

 

[oh6SR5]

Nope, it is common

http://www.toyota-4runner.org/showthread.php?s=&threadid=19371&highlight=mpg+computer

That is just one of many times it was discussed.

 

[SalsaRed4Runner]

Thank you so much... I was searching for this topic because I thought it wouold be a common issue but didn't find anything.

Looks like many others have found the same issue.

Thanks again...

 

[pipspeak]

The computer is really only good for indicating trends in your mileage, not actual mileage. Frankly I'm surprised that in this day and age Toyota cannot come up with a more accurate computer. Mine's always off by 1-2mpg, which is 5-10%. Not too good.

 

[biglatka]

normalize it

Actually it is pretty accurate. I find it is usually 7% accurately optimistic from actual calculated mileage. Knowing this, calculating in the error, and resetting the mpg readout every 3-4

 

[cdoyle]

I just went on a trip down to Portland from Washington.

The MPG was at 19.8 when I left, and was at 19.8 when I got home. Didn't change at all.

Also the Average Speed, was at 28 when I left, and was at 28 when I got home. I did an average of 70mph all the way down there and back. almost 320 miles, you would think it would at least go up to 29 (lol)

I wish there was a fix, to make all those meters a little more accurate.

 

[biglatka]

I just went on a trip down to Portland from Washington.

The MPG was at 19.8 when I left, and was at 19.8 when I got home. Didn't change at all.

Also the Average Speed, was at 28 when I left, and was at 28 when I got home. I did an average of 70mph all the way down there and back. almost 320 miles, you would think it would at least go up to 29 (lol)

I wish there was a fix, to make all those meters a little more accurate.

You have to reset it once in awhile, otherwise you could be averaging over thousands of miles. If that is the case your reading would never change much over a trip of few hundred miles, no matter how varied the trip was.

 

[Ghostface80]

My MPG reading doesnt even drop .1 when I turn on the A/C (usually have it on 2 bars on 'LO'), so I've been using it all the time since I've got my truck. Does A/C really not take that much gas? I always thought it did in my previous cars so I rarely used it unless absolutely necessary.

 

[pipspeak]

Does A/C really not take that much gas? I always thought it did in my previous cars so I rarely used it unless absolutely necessary.

I think it depends on the car. Some AC compressors (from what I've read) will take more power from the drive belt, others from the battery. Overall, however, a 245HP engine is not going to have to work much harder at all to run a compressor, so I would not expect much in the way of a mileage hit.

On some cars (Nissans spring to mind) you cannot actually turn off the AC... they're just on auto climate control the whole time. Glad Toyota hasn't gone that way. I only run AC when the temp's above 75F. Prefer fresh air.

 

[Ghostface80]

I only run AC when the temp's above 75F. Prefer fresh air.

LOL, must be nice to be in the bay area this time of the year. I only turn it on past 90F. Plus I live in the smogiest area in the western U.S.

 

[Falls]

I was playing with my avg. speed , I put the cruise on 55 mph on a flat road with no wind condition's, and moderate 65 degree temp. I then reset the comp. and kept rolling , it took a while but my average mph came out to exactly 55. I don't really know if that's a test to anything , but was just playing around and wanted to se how acurate it would show. I was surprised it came to 55.

I think if you doing a test or going on a trip you should reset it. I personally think it's pretty accurate. I've checked my milage and for strictly city driving my avg. mpg is 22 mph and 16.5 mpg. I checked it the old fashioned way and came out almost exact IMO @ 16.3 which is accurate enough for me , BUT this does not acct. for the increase in tire size either,which would actually would have traveled more mile's than the odo.reads, which should result in slightly higher milage.