It seems pretty off. I recently changed some filters, replaced pressure switches, had to replace a faulty Pedal Positioning Sensor, and did an oil change and my first of a 3x3. My mileage *seems* to have improved, but my MID suggests it's the same. Yes, I did reset it after the work was done.

is the MID accurate, or is it simply a guesstimate?

 

My MID, as far as MPG is concerned, is within less than one half a mpg. Now the oil change life, I don't even bother with that. I change my oile every 3,000 miles, and the oil life shows at least 50% left.

Oh, I also use the Torque app on my phone and the average mpg is nearly identical to the MID.

 

The MID mileage is off by an admitted 5% ( http://www.odosettlementinfo.com/ ) for 04-06 TLs (MID mileage reads higher than actual). Not sure if/how that factors into the MID MPG estimate, but theoretically, if would seem that the MID MPG should be 5% higher than actual MPG.

Since the MID only reads in whole numbers and there is no documentation to determine when/if it rounds, it's really hard to put a finger on true accuracy. But on my TL, I have never found it to be off more than a possible 1.4 MPG, and quite probably less.

e.g. I manually calculated 29.5 MPG, MID reads 30 MPG. Is that 30.0 MPG or 30.9 MPG? Or is it something between 29.5 MPG and 30.4 MPG? Who knows?

(Disclaimer: I never used "corrected" mileage [e.g. subtract 5% from MID mileage figure] for my manual calculations, but I should have).

 

Thanks guys,

How exactly does it compute the mileage? Anyone know? Whatever it is, it must compensate for driving style, issues with the car (severely clogged air filter, etc.), weather, tire inflation, etc, right? I'm curious how it actually tracks mileage.

 

Miles is miles... . If you are referring to the maintenance alerts that come on the MID, refer to your owner's manual.

"Based on engine operating
conditions and accumulated engine
revolutions, the onboard computer in
your Acura calculates the remaining
engine oil life."

Click on this line and goto pg. 195

 

Miles is miles, but my gas mileage is dependent on many factors, no? If I drag race back and forth on a strip, as opposed to gingerly covering the exact same distance, than obviously my mileage will be different. If I do the same experiment on half flat tires as opposed to overinflated tires, that too will affect my mileage. Factor in any mechanical issues, tire pressure, weather, etc., and there are many factors that go into our gas mileage. How does the MID know those factors? That's my question.

 

pretty sure the MID just divides miles by gallons used....

gallons used is gallons used....

 

So if that's the case it's not really accurate at all. A brand new TL will report the same mileage as one with a spark plug pulled, timing belt off by a tooth, and three half-flat tires.

 

Not at all. It's all based on miles traveled and gallons used. Period. It doesn't care about other items, it's strictly physical measurements: distance over quantity. Don't get MPG estimates confused with the maintenance intervals....

 

all of those factors the OP stated (tire pressure, driving style etc) do not influence the actual calculation of the MID for MPGs. THEY will however influence your overall MPGs, maintenance intervals, wear and tear etc of the vehicle. OP-the MID probably calculates the MPGs like we would paper and pencil like nfnsquared mentioned. it seems you are overthinking the MID system.

 

Pretty sure that something like the MID is using injector duty cycle combined with fuel pressure to figure out how much fuel is used. Miles would just be odometer miles. Its only as accurate as it can meter those two items.

 

Yep, I assume the ECM is tracking injector duty cycle to determine fuel quantity used.

 

Again, thanks guys.

nfnsquared... Are you a casual Rush fan, or are you a musician? Just curious.

 

Rabid

 

I guess my MID must be more accurate than most. I always fill my tank full then I calcuate from the MID numbers that I've burned 15 gallons. Then when I go fill it back up it's always within a tenth or two of 15 gallons.

 

Nice. As am I. Also a bass player. A bass player who longs to some day be 1/8 as good as Geddy!

 

Rush.....R&R Hall of Fame baby!

 

Last week I got to go on a nice 1000 mile road trip with lots of diversity of driving style to put the MID under the test.

Below are some photos of gas receipts along with the calculated actual MPGs. A few comments:

1. The average speeds of each leg of driving varied greatly. I had one tank with an average speed of 75 MPH and another tank with average speed of 27MPH

2. The errors with the MID always involved topping off a mostly full tank which involved filling < 6 gallons of gas. Perhaps this is what some people are experiencing when they write that the MID is too optimistic? I normally don't top off my tank like this when at home.

3. Notice I write the distance, average MPH, and MID's MPG in pencil at top of receipt. I do before resetting the MID each time I fill up the tank.

Receipts North bound:



Receipts South bound:



FuelEconomy.gov results:

 

Another thing to take into account, is that you are assuming the fuel pump at the gas station is accurate. Some states, like Oregon, have no laws/regulations with regards to QA of fuel dispensing stations, wheras states like WA have a department of Weights and Measures that come out regularly to certify the pumps, and test for accuracy, etc. A long time ago, there was a news article about some of the gas stations in Portland, and showed that many stations had mis-calibrated pumps, and of the mis-calibrated pumps, something like 99% of them were mis-calibrated in the gas station's favor.

I've witnessed this first hand, as I used to live there, and one time I got gas near my old high school. The attendant pumped 10 gallons in, (illegal to pump yourself in OR), and the pump said 10 gallons, but I only got 5 gallons of actual gas, based on my fuel guage. (Normally, 10 gallons would have brought me near F, but I didn't even get 1/2, it was closer to 1/4.)

Since I moved to another state, where I can pump the gas myself, and there is a certification sticker on the pump with an inspection date on it, I haven't had these kinds of shenanigans happen anymore.

 

Love it! I actually live 15mins from the Lakeside Park they wrote the song about. I bring my kid to the carousel in the spring/summer! ...sorry OP! lol

 

Yes gas pumps not being calibrated will cause problems- fortunately CA also has pumps calibrated and regulated. Costco which I pump probably 95% of my gas does there own quality control as well- I'm pretty confident in getting a decent fill at Costco.

In doing this study and looking at records of the last 6 years, I can say that my errors have been with <6 gallon fills. Since I know there are people on this forum that say the MID is very optimistic, I'm wondering if that's what they're doing?

As you can see from m y gas receipts, when I go over 150 miles the MID is pretty accurate.