Author Topic: MPG for those interested  (Read 142610 times)

madasafish

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Re: MPG for those interested
« Reply #15 on: December 03, 2020, 11:20:21 AM »
I would expect a hybrid - where the engine switches on and off regularly - to gave a cooler running engine. In winter with colder air through the radiator - the engine may run a lot cooler and hence be significantly less efficient when running than an ICE car.

John Ratsey

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Re: MPG for those interested
« Reply #16 on: December 03, 2020, 11:43:48 AM »
I would expect a hybrid - where the engine switches on and off regularly - to gave a cooler running engine. In winter with colder air through the radiator - the engine may run a lot cooler and hence be significantly less efficient when running than an ICE car.
I was surprised that Honda didn't provide thermostatically-controlled blinds for the radiator to restrict cold air entry to the engine compartment to address this problem which is entirely foreseeable. I think they did this on the new CR-V. The cold engine problem is exacerbated by the cabin heating sucking whatever heat there is out of the engine coolant due to Honda not designing the electrically-operated aircon to run in reverse as a heat pump plus, on the Crosstar, the absence of the undertray will also help keep the engine compartment cold.

While the WLTP testing is an improvement on what came before, it should have included a cold weather stop-start traffic test to help focus vehicle designers' minds on this aspect. Longer journeys with the engine running continuously under moderate load won't have the cold engine problem but I reckoned it took at least 5 miles to get my HR-V running efficiently on a cold day.
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JazzMusic

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Re: MPG for those interested
« Reply #17 on: December 03, 2020, 12:24:40 PM »
I would expect a hybrid - where the engine switches on and off regularly - to gave a cooler running engine. In winter with colder air through the radiator - the engine may run a lot cooler and hence be significantly less efficient when running than an ICE car.
I think they took care of this. In the old Honda Insight the base coolant temp was about 10 deg C lower than on other Hondas. But even then some owners have fitted cardboards in front of the radiator to extract more heat for more efficiency and more heating in the cabin. But the effect was in the single digit range, not 10 or 20%.

I was surprised that Honda didn't provide thermostatically-controlled blinds for the radiator to restrict cold air entry to the engine compartment to address this problem which is entirely foreseeable.
+1. Not sure if it was cost cutting, max reliability or no big impact.

Two things would be interesting to know: engine revs and coolant temp, both seem to be not available for the driver.

One more observation: the engine revs higher than in summer. More noise, not disturbing, but noticable.

EDIT: found a solution for WT and RPM: if you pull the steering wheel back there's is enough space for a scangauge.
« Last Edit: December 06, 2020, 12:42:44 PM by JazzMusic »

JazzMusic

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Re: MPG for those interested
« Reply #18 on: December 08, 2020, 11:58:25 AM »
I've some more observations with my ScanGauge.
As John Ratsey pointed out somewhere in this forum a cold engine starts with 1600 rpm until the coolant temp is 40 deg C and charges the hybrid battery, I guess to warm it up too.
After that EV is available unless you start the heating. In all my cars I've let the engine warm up before using cabin heating. When I switched the heating ON to 22 deg C the coolant temp lost 10-20 deg C, BUT not so in the new Jazz.
When I active the heating in the Jazz the engine management seems to let the engine more often to supply heat for the cabin. The coolant temp range is between 60 and 80 deg C.

John Ratsey

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Re: MPG for those interested
« Reply #19 on: December 08, 2020, 07:56:38 PM »
In all my cars I've let the engine warm up before using cabin heating. When I switched the heating ON to 22 deg C the coolant temp lost 10-20 deg C, BUT not so in the new Jazz. When I active the heating in the Jazz the engine management seems to let the engine more often to supply heat for the cabin. The coolant temp range is between 60 and 80 deg C.
I also keep the cabin heating off until the engine has had opportunity to warm up. Using the heated seats will help to keep the front seat occupants warm and also uses some of the electricity. However, this doesn't help with demisting the windscreen.
2022 HR-V Elegance, previously 2020 Jazz Crosstar

JazzMusic

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Re: MPG for those interested
« Reply #20 on: December 09, 2020, 10:12:52 AM »
I also keep the cabin heating off until the engine has had opportunity to warm up. Using the heated seats will help to keep the front seat occupants warm and also uses some of the electricity. However, this doesn't help with demisting the windscreen.
The engine heats up pretty quickly without doing much driving.
I'm using heated seats, heated steering wheel (almost always in winter), set aircon to recirculate and switch the fan OFF. A/C also OFF. No problem with misting so far when I've let the A/C to loose the moisture by switching it OFF miles before I let it sit overnight. When the engine is warm enough (60 deg C) I switch the fan ON and set the temp to 22-24 deg C and use fresh air but still with A/C OFF.
A/C ON is a culprit in winter. Sure it helps to demist the windows but it stores so much moisture that you can't switch it OFF the next time you start a cold engine/interior. You're forced to leave the A/C ON to demist the windows.
I know I'm using A/C not much (or just on a monthly base) but never had any problems with it in several cars but I also do an A/C service every 2-3 years which contains demoisturing, new oil, filled freon up to the top.
« Last Edit: December 09, 2020, 10:16:08 AM by JazzMusic »

Expatman

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Re: MPG for those interested
« Reply #21 on: December 11, 2020, 04:17:32 PM »
Why would you switch A/C off? Surely leaving it on with recirc will dry out the air and so reduce condensation more be quickly. That's the advice in my Skoda Yeti's manual - also has heated windscreen which quickly eliminates any condensation anyway.
Pity Jazz doesn't offer heated windscreen even as an option, I believe heated windscreen is a real safety item and more important than some of the more esoteric items that are included as safety items.

JazzMusic

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Re: MPG for those interested
« Reply #22 on: December 11, 2020, 04:56:58 PM »
Why would you switch A/C off?
Worse fuel economy and even drier air than outside.

IanG

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Re: MPG for those interested
« Reply #23 on: March 09, 2021, 05:37:10 AM »
In the countries where a non hybrid Jazz is available, the digital instrument cluster includes a bar display rev counter at the top of the display and the battery charge gauge is replaced by a water coolant gauge.
I guess on the hybrid model, with the ICE only operating part time, a rev counter is deemed less useful, particularly during the times when the ICE is acting as a generator and the revs may be more constant. Possibly, as the engine temperature is less likely to remain at a consistent regular running level due to part time ICE operation, the coolant temp gauge is replaced with a two stage warning light indicator, to alert if coolant temp is too high.

On the non hybrid models, the blanked out switch near the gear selector is fitted with a start/stop system deactivation switch.

In some markets there is also a heated screen switch in the panel which includes the parking sensor switch. I think this may just heat the windscreen in the wiper park position area, as is the case on some Kia vehicles.

I wondered why the dash lighting illumination switch was over large, then saw that, in some countries, the lower half of the circular switch features a ‘TRIP’ button. Assuming this resets the trip counter or accesses the trip counter mode, rather than accessing the trip counter using the menu system. Perhaps these models have a less compressive range of trip counter features, so a simple reset button is all that’s required, same as the trip reset buttons that feature on many analogue instrument clusters.

Would be nice to have the rear seat centre armrest that some countries receive, particularly as the rear accommodation is generous for a small car. Some of the UK specs show this as a standard feature but I haven’t seen any UK models with it.
Strangely, the cars that have rear centre armrest often seem to have a tray between the front seats, rather than a front centre armrest/cubby box, which I’d have thought was more useful.
« Last Edit: March 09, 2021, 07:34:17 AM by IanG »

Arthur70

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Re: MPG for those interested
« Reply #24 on: March 12, 2021, 06:14:08 PM »
To John Ratesy.

Great figures there John.  Do you make a conscious effort to drive economically or is that mainly motorway mileage.

Just curious.
Art

John Ratsey

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Re: MPG for those interested
« Reply #25 on: March 13, 2021, 08:45:36 AM »
Great figures there John.  Do you make a conscious effort to drive economically or is that mainly motorway mileage.

Just curious.
A valid question. I'm happiest pottering along on a rural A road at 50mph and do my best to avoid motorways. However, when on a motorway I tend to use the lorry lane at 60mph with the occasional burst of extra speed to get past a lorry.

The Crosstar isn't a very aerodynamic shape which means that the drag losses mount up at higher speeds. I don't like driving in towns either but have noticed that the hybrid system is happy under those conditions as it also is during stop-start traffic on a motorway.
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Jazzik

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Re: MPG for those interested
« Reply #26 on: March 22, 2021, 05:27:44 PM »
Just out of curiosity, I have compared the actual measured average fuel consumption of 3 competing small hybrids on "Spritmonitor" (www.spritmonitor.de/en/) : De Honda Jazz e:HEV, the Toyota Yaris Hybrid and the Renault Clio E-tech.
Of course this is not really representative yet: few cars, little miles.
The (preliminary) conclusion, however, is a bit surprising. The Jazz (62 mpg) and the Yaris (63 mpg) virtually no difference, the Clio however, at 52 mpg, is quite disappointing.

It looks like "Japan rules"  :D
« Last Edit: March 22, 2021, 05:39:33 PM by Jazzik »
If nothing goes right, go left!

guest10167

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Re: MPG for those interested
« Reply #27 on: April 04, 2021, 08:40:01 AM »
Just out of curiosity, I have compared the actual measured average fuel consumption of 3 competing small hybrids on "Spritmonitor" (www.spritmonitor.de/en/) : De Honda Jazz e:HEV, the Toyota Yaris Hybrid and the Renault Clio E-tech.
Of course this is not really representative yet: few cars, little miles.
The (preliminary) conclusion, however, is a bit surprising. The Jazz (62 mpg) and the Yaris (63 mpg) virtually no difference, the Clio however, at 52 mpg, is quite disappointing.

It looks like "Japan rules"  :D

Indeed!
What I find even more interesting, is that the Jazz is bigger, a lot heavier and more powerful than the Yaris, but fuel efficiency is similar. So for me, Honda rules  ;)

guest10167

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Re: MPG for those interested
« Reply #28 on: April 04, 2021, 09:07:21 AM »
Just had my first refuelling.

799.7 km (about 497 miles) - 32.59 litres (about 7.2 gallons) - 4.08 l/100 km (about 69.24 mpg)

The car indicated 3.9 l/100 km, so it's about 5% off

Mostly commuting with speed limits of 50-70 kph in "D" with ECON mode on and use of ACC where possible. I go to work before 6 am, which means a lot of cold starts. The car sits in the garage overnight. I only use aircon when I need it, for demisting or when the car is too hot (not often so far). Heating is on, but usually not higher than 20 degrees. There were only a few short stretches of motorway, where I try to stay between 110-115 kph.

I'm quite pleased with this fuel economy. The car is less than a month old, and apart from last week, the weather hasn't been warm yet. So I expect to get even better mileage in the future!

Jocko

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Re: MPG for those interested
« Reply #29 on: April 04, 2021, 10:45:46 AM »
69.24 mpg
That is excellent. That is the BEST I have ever achieved with my Mk 1. Come the summer, you should easily exceed that.

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