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Hey guys, I have an Insight 2011 and am pretty happy with it.

So I noticed this for the first time. I typically reset the "B" odometer every time I fill up the gas tank. So currently, I have driven 390 miles and my mileage shows up as 47.6. However, my low fuel light came on. From what I understand, when that light turns on, I have 1.8 gallons left. So it means that I used up around 8.8 gallons to drive 390 miles, which gives me a mileage of 44. so what gives? which one is correct?

Has anyone else seen this behaviour?
 

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The fuel economy displayed on the MID above the steering wheel is usually optimistic by about 2 mpg. Thus, when the MID reads around 47 mpg, then you are likely getting around 45mpg.


Sent from AutoGuide.com Free App
 

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When you fill the tank and zero out the trip meter, do the division problem:
miles divided by gallons equals MPG. That is the real MPG. The MID is just a guess and as twulz says, about 2 MPG optimistic.

Many folks use an app called Fuelly and just enter the figures in their smartphones when refueling.

https://www.fuelly.com/

My wife has a little book she writes this info in.

I always print the receipt and write down the trip mileage and MPG from my calculator. I also try to write down the total miles on odometer as this helps me figure the miles driven if I forget to zero out the trip meter.

Both my wife and I take mileage deductions on our schedule C tax forms so having some details about business use makes taking the time to write things down worth it.

There is a way to program the MID to zero out the trip meter whenever you refuel. See your manual.
 

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The fuel gauge/readout is definitely optimistic (between 1 to 2 mpg) but that is by design. Gasoline standards are all over the map and the readout uses an average based on how the car is driven.(not taking into account how the gas is formulated for example: 10%ethanol fuel will also lower your mpg or some states require a specific additive and so on)
 

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When the pump says 8.8 gallons, that is what you pay for. True.

But did you really get 8.7 gallons? Was the hose full when you started?

Did you fill the tank a little less last time and squeeze a bit more in this time?

400 miles / 8.8 = 45 mpg or 400 / 8.7 = 46 mpg.

I agree with the E10 getting less mpg too.
 

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I have found if using the same pump when filling up the MID is considered accurate IMO.

As the above comment there are multiple variables that play part when filling up. temperature, car angle, weight distribution, fuel hose having fuel in the line, etc, etc. bottom line it's near impossible to replicate the fuel filling of the previous tank unless you physically remove the fuel tank and measure/weigh the gas you put in each time. So I am sure there is always a margin of error...

I have found with my particular car the range is ~1.5mpg in the +/-. I've had a few that calculated out a little less and a few that calculated a little higher then the MID display.
 

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MID on my Insight can vary a bit. I've seen mostly 2.0 mpgs of optimism, but latest tank was just about 0.7 mpg off.
 

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Anyone use ODBII to check this?

Hello, after the VW incident and with Gas prices creeping up again I was thinking about getting a App tracker https://www.automatic.com to check my driving style on different routes to work. Has anyone used any plugin adapters. I had used fuelly but it didn't do well as I often fill up at half a tank. Thoughts or is it more of math problem?
 

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As is pretty usual, the speedo over-reads by about 4% and the odometer under reads by the same. I've checked the speedo vs GPS and it's usual for the odometer to be off by the same in Japanese cars (recent Honda and Mazda certainly).

So buy my reckoning that makes the MID fuel consumption tracking about bang on.

I think Honda know exactly what they're doing with this one ...
 

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Well, my latest tank was an indicated 70.5 imperial mpg. In reality, once I did the calculations, it was 64.1 imp mpg.

Same pump and approx time of day too.
Can you explain how you are getting such great mpg?
I see in your signature you've done some mods - is there more info on these?
Thanks!
 

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Can you explain how you are getting such great mpg?
I see in your signature you've done some mods - is there more info on these?
Thanks!
Imperial gallon guys and gals will always get better mpg than those of us using the more pedestrian regular US gallon measurement. Imperial gallons makes it Royally difficult to compare mpg sometimes.

1 Imperial gallon = 1.20095 US gallons

So basically every 5 Imperial gallons, makes a little over 6 US gallons in the tank. By 10 Imperial gallons, they have over 12 US gallons in the tank. Skews their figures a tad, compared to US calculated MPG.

60 mpg (US) is attainable with our 2nd Gen Insights, but only under certain driving conditions, like low traffic rural roads where speed limits range mostly from 35 to 50 mph under reasonable temperatures between 55 and 80 degrees, preferably with low humidity levels.

Stop and go traffic, high speed driving and cold Winter temperatures will significantly diminish MPG. Good quality oil, Low Rolling Resistance tires, properly inflated, and easygoing anticipatory driving technique will help bring your MPGs up significantly.

The MID does a pretty good job with MPG. Mine ends up close to calculated most of the time.

I filled the Insight tank late yesterday afternoon since I needed to fill gas tank for mower and snow blower (just in case). On way down to gas station 6 miles away MID said 54 mpg. Calculated gallons to miles turned out 53.8 MPG. It was a cool 32 degrees and dropping. Generally uphill to the house from gas station, plus we had a good head wind. Speed limit was 40 mph that everyone stretches to 45 mph or more depending on traffic. Engine not fully warmed up since it's only a 6 mile drive, and by the time I got back to the house, the MID showed 45.3 mpg. Even in our cool weather, the MPG will continue to go up slowly as I drive the next week or two and should end up in the 50 to 53 mpg level. Depends how cold it gets or stays.

Experiment with your driving style. And make sure you inflate the tires to at least recommended pressure. Cold air lowers tire pressure. Each 10 degrees of temperature drop causes about 1 psi of tire pressure drop. I keep mine 40 psi front and 38 rear. I check them every couple of weeks or so and adjust as needed. The car us currently running on Bridgestone Ecopia EP422 tires as a reference point.
 

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The car is reasonably accurate but not perfect .. nothing is .. Any meter has a +/- accuracy range ... including the often over looked device called a gas pump.

An error of 2% does not tell you if 1.9% of that was pump error or if 1.9% was car error.

Same for other devices , including GPS .. Again the GPS will be reasonably accurate .. but if your GPS disagrees with the dash by 2% ... that alone does not tell you which one is off by how much .. is the GPS off by 1.8% or is the dahs off by 1.8% ... etc.

There have been many cases of the pumps being known to be off by significant margins.
Example , Less than ~2.59% pump error (6 out of 231 cubic inches) , might not even get any fine at all... even if the pump is shown to be 2.4% or so shorting customers.
 

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Totally agree. Lots of room for fuel calculation error, pump calibration, environmental temperature, tank level, auto shut off discrepancy and the rest. I've tried to use the same pump, same car placement, same slow fill rate at the same station most of the time to try to mitigate some of the variables, but there still will be some. Can't make it perfect.

I would imagine that after some time, you should end up with some reasonable average that will be fairly close to reality. MID generally indicates slightly higher than calculated MPG, but a couple of times it's been right on or a tad lower.

I tend to use the running MPG display on the MID to help adjust driving to maximize fuel efficiency when I can. It's a game and keeps the drives interesting for me.
 

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I have a 2010 with 75,000 miles and minus 2.5 from the indicated mpg and always get witin a tenth of a gallon on fillups. Since the software upgrade a year or two ago I've jumped from 41-43 to 45-47 during my work commute in CT. I run my tires at 50 psi and get incredible rolling traction but slip on takeoff during wet or worse weather.
 

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What tires are you running on the car. 50 psi is pretty far up there. Watch the center of the tread for wear compared to the sides.
 

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I always run 55 lbs in my G1. I have never seen abnormal wear in the center of the tread. I think this notion came from old bias ply tires, which WOULD behave this way. I believe the belts in radial tires pretty much prevent this from happening.

Sam
 

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Really depends on the tire width and construction somewhat. Typical signs of over inflation of a tire is center tread wear above that found on the shoulders of the tire. Under inflation would produce the opposite effect, with more shoulder wear than central tread area of tire.

This would occur on radial or bias ply tire. I haven't seen a bias ply tire in years. A first gen Insight might have quite narrow tread section, so it may not be as apparent.
 
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