Author Topic: Insane MPG  (Read 13897 times)

BigRon

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Insane MPG
« on: August 27, 2020, 06:50:02 PM »
Have a look at the attached photo.

It shows the mpg I managed, according to the trip computer, driving home this morning. Must admit that it was about 60% downhill the rest on the flat with no uphill. (The earlier journey was mainly uphill and I must admit I didn't record it).

My trips are set to reset as follows:- Trip A when car is switched off, Trip B on refueling.

DomnicZZ

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Re: Insane MPG
« Reply #1 on: August 27, 2020, 07:39:47 PM »
That’s indeed some 3 figure MPG!

 I did read about someone who drove a Nissan Leaf from the top of a hill to the bottom, and the battery charge Level went up by a few percentage points. I wonder what figure it would display just going downhill on regen braking without the engine having to kick in.
My Jazz: 2004 CVT

BigRon

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Re: Insane MPG
« Reply #2 on: August 27, 2020, 08:43:51 PM »
I have been testing a bluetooth OBDII with a tablet running car scanner which gives %age battery charge as one of the parameters it shows as against Honda's bars but the pairing between the OBDII and the tablet decided to fail this morning. It may be the OBDII (only cost £5.00) failed or it could be the canbus issue that is delaying hardwiring my dash cams.

Honda's battery bar gauge was showiing full bars for quite a bit of the trip.

John Ratsey

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Re: Insane MPG
« Reply #3 on: August 27, 2020, 08:50:14 PM »
I've noticed that the mpg for my Crosstar is very sensitive to the height difference between start and end points. For example, a 50m height difference over 30 miles can result in 75 mpg going down and 65mpg going up (although the wind may also be a factor). And on shorter trips the battery charge level at start and end can also significantly affect the mpg.
2025 Jazz Advance, previously 2022 HR-V Elegance, previously 2020 Jazz Crosstar

Westy36

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Re: Insane MPG
« Reply #4 on: August 27, 2020, 10:20:03 PM »
MPG figures to be very proud of!  ;)

Jocko

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Re: Insane MPG
« Reply #5 on: August 27, 2020, 11:07:52 PM »
Excellent mpg. Height from start to finish can make a big difference. I use a particular route regularly because it gives great mpg. 6.3 miles with plenty DFCO and I have registered 108 mpg on my ScanGauge start to finish. In the opposite direction, I would be lucky to get half that.

BigRon

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Re: Insane MPG
« Reply #6 on: August 27, 2020, 11:38:05 PM »
Yes Jocko I was driving from East Kilbride To Rutherglen so quite and elevation drop, not exactly sure the difference but I think its between 100 and 200 metres??

JazzMusic

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Re: Insane MPG
« Reply #7 on: September 05, 2020, 06:29:24 PM »
Any mpg runs have to start with a cold engine and have to end at the same altitude. Everything else is severe cheating you can't trust in. :P
I did my first mpg test run today and got 73 mpg or 3.2 l/100 km. Not bad as a starter.

I didn't use the ECON mode. I've noticed that the charge level of the Liion-battery remains at 3 to 6 bars, a little bit low for my taste. I'd love to see it in the upper half.

John Ratsey

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Re: Insane MPG
« Reply #8 on: September 05, 2020, 08:28:24 PM »
I've noticed that the charge level of the Liion-battery remains at 3 to 6 bars, a little bit low for my taste. I'd love to see it in the upper half.
The 6 bars on the battery covers up to 69% charge. The remaining capacity is for when you go down a significant hill and have to control your speed. In addition, most wear on the Lithium battery technology occurs when charging to full and discharging to empty so Honda tries to minimise use of the ends of the charge range. I suspect the bottom part of the battery is reserved for when a short burst of power is needed for quick acceleration but it isn't normally used as the engine comes on when the battery gauge is down to 3 bars.

The bottom line is that a higher capacity battery would improve economy a bit more - if the battery pack is actually the size indicated in the schematics then it's surprisingly big for 1kWh rating but it must include arrangements for thermal management.
2025 Jazz Advance, previously 2022 HR-V Elegance, previously 2020 Jazz Crosstar

JazzMusic

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Re: Insane MPG
« Reply #9 on: September 05, 2020, 08:56:03 PM »
Does anybody know what the ECON button does exactly?
Does it have a big hit on acceleration?
Does EV get more involved?
Does it really improve mpg? By how much?

Jocko

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Re: Insane MPG
« Reply #10 on: September 05, 2020, 10:55:17 PM »
The ECON mode helps you improve your fuel economy by adjusting the performance of the climate control system and the accelerator pedal response (page 405 of the manual). So if you are not too worried if the temperature changes by a degree or two and the acceleration is not all it can be, then I am sure it will save fuel.

JazzMusic

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Re: Insane MPG
« Reply #11 on: September 06, 2020, 08:39:33 AM »
The ECON button does less than expected. Or they didn't list all its (complicated) effects. The biggest hit is A/C which I only use above 25 degrees C. 

cjp2k20

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Re: Insane MPG
« Reply #12 on: September 06, 2020, 09:50:46 AM »
It does indeed affect acceleration, but that's not to say it takes it away from you if you want it. It's almost as if it changes the power gradient of the pedal so you just need to give a bit more than without ECON mode. For that reason I'll be leaving it enabled; it takes away that slight temptation to move away more quickly but the power is still there if I need it.

I got similar MPG on two similar drives, with ECON winning out slightly (I don't recall the figures). In some conditions I suppose there may be a bigger difference.

I can't comment on the effects on A/C given the cooler weather currently.

ColinB

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Re: Insane MPG
« Reply #13 on: September 06, 2020, 11:32:11 AM »
The biggest hit is A/C which I only use above 25 degrees C.
I can't comment on the effects on A/C given the cooler weather currently.

Just a warning about that. If you leave the A/C off for an extended period (over the winter months, say) the pipework seals will dry out and fail, the refrigerant will leak out, and you’ve got a very expensive repair bill. As I know to my cost from a previous car. It’s much cheaper in the long run to leave it running; personally I’ve never noticed any difference in mpg with/without it anyway. Even in winter A/C is essential to keep the screen demisted.

culzean

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Re: Insane MPG
« Reply #14 on: September 06, 2020, 12:05:57 PM »
The biggest hit is A/C which I only use above 25 degrees C.
I can't comment on the effects on A/C given the cooler weather currently.

Just a warning about that. If you leave the A/C off for an extended period (over the winter months, say) the pipework seals will dry out and fail, the refrigerant will leak out, and you’ve got a very expensive repair bill. As I know to my cost from a previous car. It’s much cheaper in the long run to leave it running; personally I’ve never noticed any difference in mpg with/without it anyway. Even in winter A/C is essential to keep the screen demisted.

Yup, leave it on all the time,  above 30mph it costs more mpg in drag to leave windows open than the aircon.  As you say using the aircon can save you expensive bills,  and the cost of gas for newer models is eye-watering....
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

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