I have "reverse" calculated what my indicated "lifetime" tank averave would be as 39.54 mpg. My current actual is 38.69. This is after 21 tanks, each time I filled up by letting the pump kick off then squeezing two times to try to assure I topped off at as close to the same level as possible.

This is actually fairly close. HOWEVER, if you click on my milage link below and then hold your mouse over "more" on my tank information I have listed the indicated tank reading with each tank. As you can see several are very close and a few are as much as 2 mpg different, and not always on the same side of error. I wish I could figure out why it varies.

I can't explain it but I know that today I was disappointed with my 39.8 mpg performance on my trip but only because it was indicating 42 mpg and I was in hopes of bringing my overall average up more than the 0.1 mpg that it did.

Just thought I'd pass this info along as it's a question that's came up several times and because 1) I've got so many tank readings, 2) I've tried to be consistant in filling, and 3) because I've kept track of all my indicated readings and was able to back calculate what my overall indicated would have been.

Hope it answers question

 

I have a Sienna which also computes the mileage and I always check it against the pump. The computer on the Sienna is generally high by about 15%. However, on occasion it will show either a smaller or a larger descrepancy. One factor which no doubt has some effect is the temperature of the gas. The pump is pumping a certain volume. As the gas expands and contracts due to temperature you can get more or less gas into your tank. This is not the only effect. The gas pumps themselves are no doubt off. Each time I fill up, I am using different pumps.

 

mine runs real close on actual fill vs indicator.

 

I've been filling up when the needle falls to about 1/2 on the fuel gauge. At my first fill-up, the NAV display showed 36.6 mpg and the ECO display showed 36.0. My actual, calculated mileage was 37.76. At my second fill-up, the NAV display showed 39.1 mpg and the ECO display showed 39.0. I was looking forward to actual results over 40 mpg. In fact, the actual results were only 36.64 mpg.

After today's fill-up, my cruising range on the NAV display was 540. Based on a 17.2 gallon tank, this implies mpg of only 31.395. I haven't figured that one out yet. I'm pretty sure I filled the tank all the way (let the pump shut off, and squeezed two more times until shut-off). Maybe by tomorrow it will work its way back up to the 640 range, where it should be.

RoLev

 

It typically shows in the 550 to 570 range on mine when I fill up (21 times now). However it does not count the "reserve" in this calculation.. Actually getting 650 is a possibility when I'm doing well if I'm willing to drive beyond the "0" miles left, but it just won't show it on the "cruising range" calculation.

 

I'm not really sure how the fuel consumption is calculated, but if you think about how many injector pulses happen over an entire tank of gas, even an extremely tiny error will be multiplied to a noticeably (but hopefully not significant) error when doing a manual calculation. I have one of these ave fuel consumption displays in my Sienna too, but I think the one in the TCH is more accurate. One advantage the TCH has is there is a time when the FE consumption reading is 100% accurate, when the ICE is not running... Something my Sienna doesn't do...

 

Mine is showing a range of 640 when I fill up the past 2 tanks. I've filled up only 5 times so far. My last tank, I ran it a bit into the reserve (63 miles past 0 miles to empty) to see if the reserve was really usable. I went 713 miles and filled up (topped off) with 16.2 gallons.

It would appear that it is safe to go 50 miles past E in a pinch. The gauge hits E very consistantly when the range drops to 0 miles to empty.

I find the indicated is about 1mpg higher than the acutal milage. This last tank indicated 45.7, acutal was 44.0. That's a little larger spread than usual. I was glad I didn't try for 750 miles on the tank. I would have been on fumes.

 

I filled up today after driving 335 miles...

"Tank AVG" showed 29.5 mpg
My own calculation was 30 mpg

Pretty close.

 

Mine is showing a range of 640 when I fill up the past 2 tanks

Since you're averaging 43.5 that would be about 630 miles for 14.5 gallons of gas, which is about what I take to fill up when I'm on "E".

I average 38.7 mpg and that accounts for 560 miles for 14.5 gallons.

In both cases we still have a little less than 3 gallons in reserve.

 

Its rather annoying that the car is reading E with 0-10 miles cruising range, but only taking 14.5 or so gallons. Obviously it has about another 60-90 miles range left, but...

Mine has been indicating about .6-1.0 mpg more than actual. Last time indicated 34.5 and was actually 33.9.