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Discussion Starter #1
I bought a 2010 Insight used, in September, with about 33,000 miles on the odometer. I actually have 2 questions.
First, since getting the car I have driven a total of 5,133.3 miles and purchased 138.689 gallons of fuel. My mileage based upon that is 37.01303 miles per gallon. However, the information computer in the car that continually shows MPG NEVER goes below 41 mpg. My question is how does the computer calculate mpg and should it be more accurate.

Second, I have always changed oil in every other car I have owned (since 1956 BTW) every 5,000 miles. However, again the computer in teh car says my oil at present is at 50%. Should I believe the car's computer or go by my past expewrience?
 

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1. If you just filled up, and you have at least 10.6 Gal in the tank, and assuming you can drive 41 mpg on each gallon, then you can add 434.6 miles to the 5,133.3 miles you already traveled. This equals: 5567.9 miles. Divide by total gallons purchased (138.689 Gallons) and you get 41.67 MPGs.

2. If you are using 2013 oil, believe the computer. If you are using up stockpiles of 1956 cans, I would go with the 5000 mile interval. :) New oils are that much better.
 

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Discussion Starter #3
More info

Thanks for the reply. Regarding the first question about mpg. The miles and gallons I mentioned were recorded over the time I owned the Insight. If I wait to get fuel after the low-fuel light comes on the first time I drove 357.3 miles and the car took 9.261 gallons for a 38.58115 avg mpg. The 2nd time I drove until low fuel light I drove 375.1 miles and used 9.368 gallons for 40.04056 mpg. The 2nd occasion was all highway driving (from Nashville to Chicago) while the first was no highway driving only around Nashville. My question, however, involves the MPG figure that is shown on the car's info computer. This indicator NEVER goes below 40 mpg and is usually in the 41-42 mpg range, but when I divide the replaced fuel into the miles driven the "actual" mpg never matches the number on the car's computer. Any explanation for the discrepancy?
 

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Well, the computer is off by 2-3 mpg. If you got different tire sizes this will further cause a problem with those numbers.

When you reset your mpg readout after a fill up, start the car and let it idle it doesnt read 0 and start to buildas you drive?
 

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Discussion Starter #5
MPG Question reply

Thanks for the reply. I have the car set so the A reading reverts to 0 when I get fuel. I manually reset the B to zero also after I put in the fuel, before leaving the gas station. It does start out very low as I usually get fuel at the end of the day less than a mile from my house and normally go right from the station home. The next day, when I start out, the first 1/2 mile I drive is a slight uphill grade which is followed by a 1.5 mile down hill run. By the end of the downhill run, the MPG is always around 45 mpg. Over the next 15 or so days before I again get fuel, the MPG will drop to around 41.2 - 41.5 but never below 40. Like I said originally, the actual mpg on the recent tank was 38.509 and the overall mpg since I first got the Insight in Sept is 37.013 (5133.3 miles using 138.689 gallons)
The tires are the original size and are kept at 41 lbs of pressure.
I was curious why there was always a discrepancy between the Info MPG and the actual MPG. Perhaps the 2-3 gap explains it.
Thanks again.
 

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The MPG info readout is to help you learn to drive more efficiently. A teaching tool really. It is not and cannot be absolutely accurate. Doing the division problem, when filling up is the only real way to know actual MPG. I would be more inclined to take the MPG numbers from each fill up and average them than to try and use total miles and total gallons. So many things effect MPG. Like the fuel you use. Honda recommends top tier fuel, but Insight owners tend to be cheapskates who buy the cheapest fuel they can find.

If your Insight now has about 38k on it, have you done any of the following:
Replaced the CVT fluid?
Replaced the engine (and cabin) filters?
Had the software updated? (see thread on that)
Replaced the tires? (I bet they are shot if original)

Indeed, buy the best 0w20 engine oil you can and then go by the MID. As has been said, it's not 1956 anymore. Honda Civics, before the oil life meters were introduced had a 10,000 mile oil change interval. I think you will find the MID getting down to 10% somewhere between 8,000 & 10,000. Depending entirely on how the car is actually driven. The computer keeps track of things like: How many starts, how many cold starts, miles driven between starts. This is not only what is measured, but certainly things like that have a big effect on oil life.
And when you do replace the CVT fluid, only use genuine Honda fluid. Changing trans fluid is easier than changing the oil in these things. If this is your first Honda, I can tell you that frequent trans fluid changes are normal. Many of us replace it more often than the MID will say to.
 

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Discussion Starter #9
See page 89 of the Insight Owners Manual regarding the MID
This shows the remaining engine oil
life. It shows 100% after the engine
oil is replaced and the display is reset.
The engine oil life is calculated
based on engine operating conditions.
For more information, see page 337 .
 

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1. If you just filled up, and you have at least 10.6 Gal in the tank, and assuming you can drive 41 mpg on each gallon, then you can add 434.6 miles to the 5,133.3 miles you already traveled. This equals: 5567.9 miles. Divide by total gallons purchased (138.689 Gallons) and you get 41.67 MPGs.
That must be that new math I've heard about. :p

From his description it sounds like bb37221 is checking his fuel mileage correctly but I agree it sounds like he added in the first fill up gallons in his calculations even though he had traveled zero miles on the fuel at that point. He should have left the first fill up out of the gallons added since he didn't use that gas before starting the test.

bb37221:
One thing I'd suggest is to check the speedometer with a GPS to make sure that your mileage is being recorded correctly. Right now you know the gallons you are putting in but the other variable is the mileage traveled. If the mph is correct then the distance should be correct and all you have to do is discount the very first fill up gallons (but keep the mileage traveled).
 

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Discussion Starter #13
thanks, but actually I did not include the first fillup in the total of gasoline purchases. Also I have compared the speed of the speedometer with a separate GPS device and the car appears to be traveling 1 MPH faster on the speedometer than on the GPS device.
 

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See page 89 of the Insight Owners Manual regarding the MID
This shows the remaining engine oil
life. It shows 100% after the engine
oil is replaced and the display is reset.
The engine oil life is calculated
based on engine operating conditions.
For more information, see page 337 .
Ah, this is a second generation feature. I don't know how I got into the second gen mpg forum; thought it was 1 st gen...
 

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Whats even more interesting is the American Insight uses miles where as the international one uses days or something different than distant traveled.
 

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thanks, but actually I did not include the first fillup in the total of gasoline purchases. Also I have compared the speed of the speedometer with a separate GPS device and the car appears to be traveling 1 MPH faster on the speedometer than on the GPS device.
Hmmm, that brings up an interesting point. Is it a constant 1 mph or does it vary with higher speeds? If it's constant then it could just be the +/-1 digit of a digital readout. If it varies then it's a real error of x%.

It could be that your tires size is a little smaller than the what the speedo is set for or your stock tires are worn down enough to cause the difference.

My 1st generation Insight came with a set of over sized tires but they are worn down to whatever the speedo is set for because it agrees with the GPS. ;)

Can your GPS can read out distance traveled?

I just remembered something, Honda extended the G1 Insight warranty because some/all? the digital speedometers were reading something like 5% higher speed and/or mileage than actually traveled (maybe due to tire wear?). You might want to check and see if there are any rumors about your car.
 

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Discussion Starter #17
The error seems to be constant but I've only compared the speed when driving on a highway. If I use the GPS to locate a destination, the speed is not indicated. The tires are the factory spec tires that came with the car and not oversized. This doesn't appear to change with increase or decrease in speed, but is a constant 1mph difference. I do have an appointment on Friday to change the CVT fluid and to check for software updates. I've experienced some weird charging situations that have been the topics of a number of posts on this site and were "cured" by PGMI/CVVT/IMA updates according to other owners.
 

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Whats even more interesting is the American Insight uses miles where as the international one uses days or something different than distant traveled.
Its just the way it counts down that's different. It shows either miles or days until the next service item (which may be an oil change but at the moment mine is just saying 90 days until the cabin filter needs changing). Last time the car didn't start reminding me about an oil change until it was showing about 500 miles remaining but I suspect that may also depend on usage.

I understand that if Honda plug the car into their computer, they can see what the next few service items are, not just what's shown on the MID.
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