Maximum MPG readout

weslich · 03-02-2008, 01:38 AM

Here's a question for the most experienced hyper-milers or Insight tech guys: A few weeks ago I reset my trip odometer while rolling on the freeway. The conditions were perfect; outside temperature, good tailwind, road surface, engine temp, etc. My instant MPG meter was maxxed out at 150 and it stayed that way for a good 8-10 miles. So I'm guessing the car is achieving 165-180 MPG for that short time, whatever. But it was definitely exceeding 150 MPG. The trip MPG display would never exceed 150 MPG, like it's physically unable to do it. Does that mean the fuel consumption meter is unable to recognize a fuel usage in excess of 150 MPG? Or does it actually record it and somehow average it in to the total tank or trip usage? I do a lot of neutral coasting (especially downhill) and the instant MPG meter stays maxxed out during a long coast. Someone please enlighten me on this.

**IamIan** · 03-02-2008, 05:56 AM

The MPG side is limited to 150 MPG.

The FE calculation is done on the metric side in how many liters per 100 kilometers.

The MPG side is calculated conversion from the LP100kM.

If you go to the metric side display it goes down to I think 0.1 accuracy... then you can do your own conversion over to MPG if you are doing better what 150 MPG.

The metric side will register and display all the way down to 0.0 liters per 100 kilometers ( Fuel Cut Mode )

The link is to the picture I took when I did my EV-Mode run I put in my signature.
http://www.geocities.com/ian_p_george/06-03-06_1523.jpg

Dgate · 03-02-2008, 10:34 AM

IamIan wrote....The link is to the picture I took when I did my EV-Mode run I put in my signature.

I must have missed another post of yours so what is your EV-mode run?

DGate

**IamIan** · 03-03-2008, 05:56 AM

The Insight EV-Mode Mod is not commonly done or used as the stock battery system does not have much Ah to keep it up for long.... and without a PHEV mod all the energy still comes from the gasoline.

Read about the concept on my web page here:
http://www.geocities.com/ian_p_george/EVMode.htm

Some discussion about it is under the MIMA thread here:
viewtopic.php?f=4&t=7188

**Roger Crier** · 05-31-2008, 03:58 PM

Hi all,

Back to this maximum readout thing...I get that the metric display can display better figures than 150 mpg..... but is there anyone who has a really long downhill road which they can start off on and get a figure on the metric display that is better than 1.5 litres per 100km ...could they then switch to non metric display to see what gets displayed? It should read 156mpg at least. If it doesn't then anyone who gets up to these heady figures is going to have to get used to running on metric.

The next assumption is that although it will not "display" better than 150 mpg, if 150 is bettered, then that mpg figure is at least used on the lifetime calculation or which ever running total you are using.

So can anyone with a local mountain go out and prove some of this..because serious Insight PHEV'S are becoming a reality as we speak so we need to know this stuff.

Thanks,

Rog, (no mountains, but better than "east angular") (UK joke for D.Gate)

**IamIan** · 05-31-2008, 05:07 PM

Quote:

Originally Posted by Roger Crier

Back to this maximum readout thing...I get that the metric display can display better figures than 150 mpg..... but is there anyone who has a really long downhill road which they can start off on and get a figure on the metric display that is better than 1.5 litres per 100km ...could they then switch to non metric display to see what gets displayed? It should read 156mpg at least. If it doesn't then anyone who gets up to these heady figures is going to have to get used to running on metric.

The metric display which is what the car uses to figure the Fuel Economy ... The metric side goes down to 0.1 Liters of Gasoline used in 100 km ... which means if you can get this low you would see the equivalent of ~2,352 miles per gallon at 0.1 L / 100 kM.

The MPG / english side of the display will not display anything above 150MPG... so if you are getting 1.4 L / 100 kM you will only see 150 MPG on the english display even though you are actually getting ~168MPG.... The Insight calculates and stores the fuel economy on the metric side... and does a conversion to display the MPG / english side.... so the LMPG will be as accurate as the Metric Side is - the limits of the conversion to MPG / english.... even if the MPG english side does not display it like the metric side does.

I do not know what the resolution / accuracy limit of the computer system is... meaning does the car keep track just down to 0.1 L / 100 kM or does it keep track lower down to something like 0.01 L / 100 kM but the metric display only goes down to 0.1 L / 100 kM?

Quote:

Originally Posted by Roger Crier

because serious Insight PHEV'S are becoming a reality as we speak so we need to know this stuff.

I doubt even a PHEV Insight will need to worry about Fuel Economy better than 0.1 L / 100 kM which is equal to about 2,352 MPG.... Although as you said... to see the benefit beyond 150 MPG the driver would have to leave MPG behind and get used to the metric....

The metric display has jumps though for instance 0.1 L / 100 kM = ~ 2,352 MPG ... but 0.2 L / 100 kM = ~1,176 MPG... the Insight will not display even on the metric side any value between 0.1 and 0.2 so you would not know where you are between 1,176MPG and 2,352 MPG.

oh no... EVIL Metric System... U.S. must fight this standard with everything we have

james · 06-01-2008, 12:00 AM

"oh no... EVIL Metric System... U.S. must fight this standard with everything we have"

Not evil metric system, evil upside-down thinking of European regulators, or whoever decided that their fuel consumption was going to be measured in liters per 100 km. (Why 100? Why not 1, or 1000? Irrational...) Would have been so much simpler if it was just km/liter.

**IamIan** · 06-01-2008, 04:56 AM

I guess the old system of calculating your own FE based on knowing how many miles you went and how much fuel you put in to go that many miles still remains a good way to figure ones FE... although this has its limits of accuracy as well.

weslich · 06-02-2008, 10:30 AM

Yes, I am beginning to question the limits of accuracy of the pumps. I ran my tank dry once just to test the range of the car under optimal conditions and was only able to squeeze in 13.4 gallons. Did a refuel recently on a non-dry tank and was able to get 13.6 gallons into the car. We need to realize that when trying to measure mpg at the pump they are not always 100% accurate. Gas pumps may not always be calibrated correctly, but there's not a lot we can do about it. I'm sure they're all in compliance within their limits of toleration. The best way is to pump into a premeasured container and then fuel the car with that. Even so, you would still need to compensate for spillage, evaporation and heat expansion. No way anyone would do that in the real world anyway. Me, I'm going to trust the Honda electronic mpg meter in the car.

**Roger Crier** · 06-02-2008, 12:19 PM

For the reasons you have just put forward, "best tank" is never going to be an accurate animal. The only way to reduce errors slightly is to top the tank brim full, then keep track of all fuel put in the car for a few tanks, then fill it to brim full at some point and then calculate on your mileage covered and fuel used. You have then removed the inaccuracies caused by relying on the pumps auto switch off system and are only at the mercy of calibration faults which should be quite small as petrol pumps should be controlled quite rigourously.

Rog