Apologies if someone else has posted this before but I seem to have stumbled on a way to reset the MPG tracked by the computer. If you hold down the display button on the steering wheel while AVG is displayed, it resets back to 0.

 

i did not know this . . . interesting.

 

you can do the same thing for any value that is reset-able like avg mph etc.

 

does anyone know how to get the MPG displayed on the GPS, i can't find it anywhere, i can't find it anywhere in my car.. its a IS350 with Nav...any help?

 

It doesn't display on the nav, it displays on the small display in the instrument panel. Press the "disp" button on the steering wheel until it comes up.

 

I am not sure I would call it a lifetime avg, since as you have found out is resettable. It would be nice to have a true lifetime mpg setting though that you can not reset.

 

Then just don't reset it. I haven't reset mine yet, and it shows 28.8 mpg lifetime with 3500 miles on the car. I don't plan to reset it.

 

Yea, not resetting it ever will give a lifetime average. But sometimes I need an avg for a particular trip. Say from point A to point B. Now that is not possible if I do not reset it. Having two average settings (like trip A and trip B) also solves the dilemma.

 

If you really want to know, and is **** enough to do this, you can jot down your lifetime MPG and your odometer miles before the trip. Then reset and do your trip. Your lifetime MPG will just be a weighted average. As you get up in miles, it should be really close anyway...

Example:
First 5000 miles: 25MPG.
Next 45000 miles: 26 MPG.

Lifetime average is 25.9... just have to remember your mileage when you reset the button each time.

 

True, but I usually fill up the gas before taking long trips, so the "tank MPG" is the one I look at. My road trips are normally to Louisiana (280 miles each way). However, if your trip is a really long one, and requires a refill, then the "tank MPG" gets reset, and you start all over again.

I see your point on the two average settings.

 

Yeah, this does work, just some simple math. However, the average Joe probably wouldn't remember to jot down the mileage on each reset.

 

I just took a trip to California and I reset it going each way to see my average mpg. It's never accurate though, so it's more just for fun. Every time I've calculated mpg it's been high by about 2 mpg.

 

Well, if you normally top off your tank, your tank level gauge is probably thrown out of calibration. Hence you get an incorrect MPG reading.

I never top off, and my MPG gauge is deadly accurate.

 

Not for me (IS350). I stop when the pump clicks, and my Miles / gallons filled always ends up about .7 to 1 MPG higher than my tank average. But I generally drive a lot of freeway and conservatively... I routinely beat the 2008 EPA highway MPG rating with my standard route.

How does the tank average reset work... can you reset it with the button? if not, can you reset it by opening the fuel door then closing it? If so, that could be a second mileage indicator for the OP.

 

No, the tank average is reset when you fill up and move the car again. It needs to be at least a quarter tank to reset too. I've filled up many times and seen the tank avg the same as when I stopped until I move the car, then it resets.