MPG... Just mentally reduce what's displayed by 10%?

I always refill when it's at the halfway mark. For several reasons. One being security. The other: I want to be the one refilling, recording the odo and trip meter info. The odometer reading in particular is good in that regard: never gets reset; if things go pear-shaped at one fill up, as long as you have the gas receipt, of volume pumped, you can lump it in with the next tank.

 

There's an app for that

I use gascubby on my iphone and fuelly on the web... I need to upgrade to ios 10 so gascubby will sync with fuelly.

 

I mean the difference between the mileage the car says you get to the gallon and your calculated mpg.

 

If our dash says 4.7 liters/100 km, for example, calculated will be 5.0 or 5.1.

 

Mine is also 7% optimistic. This seems regardless of if I'm driving light or heavy through mountains with 4 passengers. It kind of bugs me now when I hear people in the media reporting mpgs without stating if it was the dashboard or calculated.

 

Yeah it's like knowing a compulsive liar. Sad though: Toyota's the mpg leader, why not play it straight?

 

Mine's +/-5%. I usually use the computer estimation for telling my friends how awesome the car is ;-}

 

No, because the fuel economy meter is based on the odometer, not speedometer. Odometers don't have that same built-in error. At least, not anymore in the U.S., ever since the class action product liability lawyers worked over the car makers for warranty fraud.

Long ago, many of us noted that the internal computers know the speed quite accurately, and report such to the various aftermarket OBDII engine monitors (ScanGauge, Torq, and many others). The error the driver sees appears to be added right at the dashboard display, and doesn't come through on that monitor port.

 

Ha, I like it!

 

I had a friend in the car the other day who is "not PRIUS friendly" - he was quite taken aback when, as I started up, I flicked the screen to read instead of the hybrid monitor:


I think he almost choked when he saw the figures - he didn't comment - so I didn't have to say that it's not always that good.

 

Ok this might answer the question I just posted over in the Gen II Custom PIDS for Torque thread. I've had my Gen2 for about a month and my Torque App AVG MPG is usually about 7 mpg lower than my on board display on my 40 mile commute. IE today I saw 56 mph on my on board and 48 mpg on Torque but the instant MPG is about the same on both.

 

People are comparing fuel added & odometer readings to determine accuracy. I do not know where Torque accuracy fits into that.

 

This tank the difference was 3.75%, so I guess it moves around a bit. Only 2.8 mpg difference this past tank. I'll have to keep track to see how much it changes from tank to tank. I've only checked sporadically up until now.

 

I tracked the difference on my 2012 v and after 241 fill ups there was a difference of 5.3%. In my Prime the difference, after 7 fill ups, is 5.5%. Seems to be consistent between Toyota Hybrid models.

 

With consistent filling to the second click on the pump every time, mine seems to be consistently around 4 to 4.5 mpg optimistic, which is between 7 and 8% out

 

Reading some articles online (Google gas top off) tells me that fuel used after the first click is siphoned back to the gas station and therefore a waste. I'm not sure if this is true but perhaps if you tried not going past the first click for the next few tanks, you can check if you 7% decreases. I'm usually getting around 5% difference.

 

IMHO, at the first click the tank is nearly full but frothing in the fuel is still releasing a volume of vapours. Once this settles out, the level of fuel in the tank has fallen slightly, allowing more liquid to enter before triggering the tank full reaction again. The rest is arguably speculative at best and masculin bovine excrement at worst.