How much off is the MPG on the computer

[jharris2]

Re: I just called Corporate

The explanation he gave was that the software program doesn't take into account for drag factors such as wind, air temp, rolling resistence, etc.

Well, if it is software, then it should be able to be updated.

Actually, I have exceeded the mileage on the computer on a long trip, almost all highway miles. Usually, it's low, though, so I just keep it on "Range". Even that is low if you calculate range based on actual measured mpg.

 

[nathannookie]

Re: I just called Corporate

I called them, gave them vehicle information, mentioned this board and the fact that damn near EVERYONE who has a 03-04 4R has noticed this.

The explanation he gave was that the software program doesn't take into account for drag factors such as wind, air temp, rolling resistence, etc.

You might get what the computer is telling you MPG wise if you put it in a lab-like setting and eliminated as many factors as humanly possible - though that hardly seems a practical and reasonable solution.

Perhaps if the MPG software were written to maybe factor in the current speed vs expected "dragless" speed it may perhaps be more in line with reality.

I would be curious to know whether other Toyotas with similar systems produce equally flawed readings.

I still think it seems silly to have the vehicle give such information when it is inaccurate.

At least it does seem to be consistent - typically +2MPG of what you're actually getting.

I called Corporate this morning too, got a case #, but the rep ended up referring me back to my dealer, who I have just e-mailed, and didn't offer the explanation that your rep did.

Now, thinking about the answer you got...

It shouldn't matter how much wind you are heading into, what kind of grade you're climbing, or what the outside temperature is. WHY? Because the computation is simply based on two facts.

One; the number of miles you are covering... based on the odometer...or MPH x time, (however they want to calculate it).

Two; The amount of fuel you are using or have used....Gallons.

Certainly it constantly will go up and down, but on average, it still comes down to Miles driven divided by number of gallons consumed. Just like we do by hand with the gas receipts.

And...on a side note....how does the computer know how much fuel IS being used. Is it metered, or calculated by how much the computer thinks the injectors are injecting?

 

[rensho]

2mpg off here.

Wish there was a pot to tweak, or a resistor value to change...

 

[ToolmanJohn]

2mpg off here.

Wish there was a pot to tweak, or a resistor value to change...

I have also mentioned this on another thread. It seems that it should be something we should be able to calibrate easily enough. But so far no info.

 

[NoDak]

you would think since they have directions to re-calibrate the mirror compass, you could do the mpg sensor. bleh oh well, guess i just leave it on range. at least thats a heck of alot more accurate.