Author Topic: MPG for those interested  (Read 142635 times)

peteo48

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Re: MPG for those interested
« Reply #360 on: April 22, 2022, 01:15:47 PM »
57.5 mpg from latest tank. I am pretty sure this is the highest mpg I have ever recorded on any car albeit only by 1 mpg or so. Most of my driving has been in "B" mode with ECON mode selected. Did some motorway driving yesterday and I prefer "D" with Econ off for this type of driving.

PS

The old "4 mpg" optimistic thing was evident again. The fibometer said 61.5 mpg. To be honest I don't really need to record my mpg at all given how constant the 4 mpg thing is.
« Last Edit: April 22, 2022, 01:27:44 PM by peteo48 »

Jazzik

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Re: MPG for those interested
« Reply #361 on: May 01, 2022, 08:32:49 PM »
Today a short, about 40 km. (25 miles) trip with Mrs. Jazzik. Beautiful weather, 18°C and hardly any wind. Half way through we stopped for a half hour walk in the woods. We did not drive faster than 80 km/h (50 mph).
Back home, the BC showed a fuel economy of 3.3 l/100 km (85.6 mpg). I always correct the (usually over-optimistic) BC and assume a real consumption of 3.5 l/100 km = 80.7 mpg.
Not bad... the fuel tank is now about half empty and just a shame ;) that I see a consumption of 4.5 l/100 km (62.8 mpg) this far from the last fill up on the BC....
If nothing goes right, go left!

Kremmen

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Re: MPG for those interested
« Reply #362 on: May 02, 2022, 04:57:07 AM »
It does seem that up to 50mph you can get some impressive mpg, especially in warmer weather. Once over 50mph and closer to 70mph mpg drops dramatically.

Looking back to that Honda video about the h:ev efficiency, widely linked to here, the cutoff point on that was 49mph when converted from the kph used in the video.

The posted results here, and what I'm getting, have been :

50mph = 70mpg
60mph = 60mpg
70mph = 50mpg
Let's be careful out there !

John Ratsey

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Re: MPG for those interested
« Reply #363 on: May 02, 2022, 09:13:20 PM »
It does seem that up to 50mph you can get some impressive mpg, especially in warmer weather. Once over 50mph and closer to 70mph mpg drops dramatically.
I suspect that above 50mph the power output from the engine is outside the zone of optimum efficiency plus the drag losses start to shoot up (approx double at 70mph compared to 50mph). I reckon the roof rails on my Crosstar don't help and cause significnat excess drag if there's a crosswind. The Jazz is evidently optimised for urban and extra-urban conditions. If it was given a bigger engine with the optimum efficiency at higher power then I expect that the mpg under low power conditions would suffer. It will be interesting to see the real life numbers for the new Civic and I wonder if Honda will make it more tolerant of cold conditions.
2022 HR-V Elegance, previously 2020 Jazz Crosstar

Kremmen

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Re: MPG for those interested
« Reply #364 on: May 10, 2022, 05:20:54 AM »
I was always dubious about the Which? test claim that they got 91mpg out of their test car.

Yesterday I did a rare local urban trip. This involved 30mph and Ealing councils blanket 20mph limit and the result of this 9 mile 20 & 30mph trip was 130mpg !

Let's be careful out there !

guest9814

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Re: MPG for those interested
« Reply #365 on: May 11, 2022, 05:02:54 AM »
Hi Kremmen
Do you remember car presentation ?
They told during the presentation that car running in EV mode 80% of time with speed 40km/h
An if we check  Japanese Honda site they have in addition to WLTP Test result also JC08 test result
In JC08 test they get maximum 100MPG (2,8l/100km)
And if we look on JC08 test pattern we will see that most of test time car run on such low speeds and only small part of this 15 minutes test car run with speed of 80km/h (50mph)

Kremmen

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Re: MPG for those interested
« Reply #366 on: May 11, 2022, 05:58:42 AM »
Morning

All I know is what I said above. I never got above 30mph and a lot of it was at 20mph. I suspect if I'd driven longer that would have dropped as the battery needed more topping up.
Let's be careful out there !

guest9814

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Re: MPG for those interested
« Reply #367 on: May 11, 2022, 07:21:42 PM »
Aaa, maybe you get fuel economy 130 MPG because  battery on start has -50% charge and maybe engine already hot enough.
I also get readings like this (around 2,5l/100km) sometimes when I starting new trip when  engine already at it’s working temperature and battery has more then 30% charge (sorry 3 bars on battery meter) but same 3 bars can be from 25% to 42% charge.
My every day trips is same route with same speed around 40 km/h with maximum speed up to 50km/h, with glide we’re it’s possible after ice engine stopping work to charge battery, I constantly getting readings 3.0l/100km - 3.3l/100km with average on tank for  more then 300 km 3,2l/100km, but there is catch - such fuel economy possible when trip not shorter then 8 km in summer or 15-20 km in winter (+10 degrees C) if I starting that trip with cold engine.
First year of car owning i not known that and for several months did relatively short trips ~ 2-3km and my average fuel consumption was 3,8- 4,3l/100km.

John Ratsey

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Re: MPG for those interested
« Reply #368 on: May 13, 2022, 12:12:00 PM »
My Crosstar is liking the warmer weather. Yesterday afternoon I did a trip totalling 91 miles using mainly rural A roads, rarely reaching 60mph, with some much slower sections and an average speed of around 35 mph. The trip was in two parts, 26 miles where the car claimed 92.7 mph and a second part of 65 miles with a claimed 79.8 mpg. The journey was assisted by a light tail breeze, the first part included a slight height drop but was fairly level overall while the second part was through more undulating terrain with an overall height gain. The engine had been off for two hours before the start and the ambient temperature was such that neither heating nor aircon was needed.
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PTJAZZ

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Re: MPG for those interested
« Reply #369 on: May 13, 2022, 01:59:27 PM »
A couple of days ago a took a photo of my BC total average consumption as I am arriving 10.000 Km and don´t know if the BC resets the values.

On close to 9500 Km BC indicates 3.3L average and real SM 3.53L

It is like a 125 cc Scooter... ;D ;D

sportse

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Re: MPG for those interested
« Reply #370 on: May 14, 2022, 10:09:50 PM »
Speed makes a huge difference- this shows two trips on country roads likely averaging 40mph and two trips on the motorway at 70mph:



I’ve tried various things but when you are at 70mph there is hardly any difference to the mpg you get. Likely because most of the time the petrol engine is in direct drive mode and running.

Kremmen

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Re: MPG for those interested
« Reply #371 on: May 15, 2022, 05:10:05 AM »
Yep, our model of Jazz doesn't give optimal over 49.71mph (80kph)
Let's be careful out there !

John Ratsey

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Re: MPG for those interested
« Reply #372 on: May 15, 2022, 08:19:23 AM »
I’ve tried various things but when you are at 70mph there is hardly any difference to the mpg you get. Likely because most of the time the petrol engine is in direct drive mode and running.
I suspect it's a combination of a body shape which isn't very aerodynamic and the engine running well outside the zone of maximum efficiency in order to deliver the required power. I wouldn't be surprised if the new Civic with its 2 litre engine will give better mpg than the Jazz at 70mph (but worse at lower speeds).
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ColinB

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Re: MPG for those interested
« Reply #373 on: May 15, 2022, 08:47:50 AM »
I’ve tried various things but when you are at 70mph there is hardly any difference to the mpg you get. Likely because most of the time the petrol engine is in direct drive mode and running.
I suspect it's a combination of a body shape which isn't very aerodynamic and the engine running well outside the zone of maximum efficiency in order to deliver the required power. I wouldn't be surprised if the new Civic with its 2 litre engine will give better mpg than the Jazz at 70mph (but worse at lower speeds).
Plus the fact that when in direct drive the battery and electric motors are just dead weight. The Mk3 actually gives better mpg at motorway speeds ... but worse around town.

John Ratsey

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Re: MPG for those interested
« Reply #374 on: May 16, 2022, 10:47:14 AM »
Plus the fact that when in direct drive the battery and electric motors are just dead weight. The Mk3 actually gives better mpg at motorway speeds ... but worse around town.
Although there's the weight saving of having no conventional gearbox.

As for the mpg, I've looked up the official data for the WLTP tests (conducted at 23C - an untypical temperature for UK). The numbers below are the mpgs for the low / medium / high / extra high cycles = the combined result.
2019 Jazz SE manual transmission: 40.9 / 53.3 / 56.5 / 44.8 = 48.7
2019 Jazz SE CVT transmission:      37.2 / 53.3 / 56.5 / 47.5 = 47.9
2020 Jazz SE eCVT transmission:     80.7 /74.3 / 72.4 / 48.7 = 62.8

Which show that the Mk 4 gives slightly better mpg than the Mk 3 at motorway speeds but the numbers also highlight the massive drop-off in the Mk 4's mpg between the high and extra high cycles. The corresponding reduction for the Mk 3 is much less.  The WLTP procedure is described at https://en.wikipedia.org/wiki/Worldwide_Harmonised_Light_Vehicles_Test_Procedure .
2022 HR-V Elegance, previously 2020 Jazz Crosstar

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