Togfather
Posts: 9
Joined: Fri Jun 04, 2021 3:10 am
Location: Scotland
Contact: Website

Best economy for motorway drive

Hello.

I am about to embark on a long motorway drive, and will be travelling at a steady 60mph. Once the battery is depleted, which of the following will give me the best MPG economy? (all driving will be in economy mode and cruise control will be used).

A) Leave the car to sort out the balance between charging and driving without any driver input.

B) Engage charge mode and switch charge mode off when battery is full. Then repeat when battery is depleted again.

Many thanks for any help and figures anyone can supply.
mellobob
Posts: 228
Joined: Mon Jun 11, 2018 5:33 pm
Location: British Columbia, Canada

Re: Best economy for motorway drive

What I do (and I'll suggest this only to you since it seems to work for me) is to initially let the battery run down to 50%. Then I put it on SAVE. When I get to a built up area I turn SAVE off and re-engage when I hit the fast road again. This means that, depending on the mix of environments, I eventually drain the battery. At that point I don't worry, I just drive it. Depending on the number of hills, the number of times you speed up to pass, the temperature and the weight of your foot ... you should get a usage of around 6.x/100 km. I've never seen 5.x ... but we live in the mountains with lots of hills. Increasing fuel usage is easily achieved by driving faster :)
Togfather
Posts: 9
Joined: Fri Jun 04, 2021 3:10 am
Location: Scotland
Contact: Website

Re: Best economy for motorway drive

Hello. Thank you for answering, but my question still stands. I don't want to save any battery for city driving. I just want to know which option is the most economical.

Best wishes

Tog :-)
mattr76
Posts: 14
Joined: Sun Aug 30, 2020 9:16 am

Re: Best economy for motorway drive

I'm all but certain that A) will yield better results in general. Charging with the generator takes a long time and consumes fuel constantly, and I'd be surprised if you can make that up when you switch to battery.

That said, one thing I experimented with on a recent drive was charging before a planned fuel stop, to convert some reserve fuel to electricity and increase the range on the next leg. I'm not sure how well that worked out, but part of the fun of this car is experimenting with things like this!
mellobob
Posts: 228
Joined: Mon Jun 11, 2018 5:33 pm
Location: British Columbia, Canada

Re: Best economy for motorway drive

Togfather wrote: Fri Jul 16, 2021 12:46 pm Hello. Thank you for answering, but my question still stands. I don't want to save any battery for city driving. I just want to know which option is the most economical.

Best wishes

Tog :-)
Well, okay then. Use your option (A).
zzcoopej
Posts: 278
Joined: Tue Apr 14, 2015 1:57 pm
Location: Gosford, Australia
Contact: Website

Re: Best economy for motorway drive

Togfather wrote: Fri Jul 16, 2021 5:34 am the best MPG economy? (all driving will be in economy mode and cruise control will be used).

A) Leave the car to sort out the balance between charging and driving without any driver input.

B) Engage charge mode and switch charge mode off when battery is full. Then repeat when battery is depleted again.

Many thanks for any help and figures anyone can supply.
There was considerable experimentation on using the Charge mode about 5 years ago published on this forum -
viewtopic.php?t=1935
and
viewtopic.php?t=1237

The experiments found a tiny (0.5 litres/100km or less) advantage of actively using Charge mode, but not quite as you say. Charge mode isn't optimal when the battery nears full due to a reduced charge rate (this is why Tesla superchargers slow down > 80% SOC).
kpetrov
Posts: 188
Joined: Thu Oct 29, 2020 8:59 am

Re: Best economy for motorway drive

Option A is equivalent to option B but not charge to full. Charge from 0 to 30-40%. Rinse and repeat.
The goal is to be in parallel mode once the engine is working and low state of charge.
Simply there aren't any other more economical options beside parallel mode once the engine is running. Has to be combined with low state of charge as well.
My test:
https://www.facebook.com/kbpetrov/posts ... 7302894911
2018 Outlander PHEV (Canadian)
ThudnBlundr
Posts: 851
Joined: Mon Mar 12, 2018 2:18 am
Location: Yorkshire end of M1, UK

Re: Best economy for motorway drive

The PHEV needs a fixed amount of energy to get from A to B. Once the battery is empty, all that energy has to come from the ICE. So the car will have to charge the battery for way more than half the time whatever you do, and saying that using CHRG is less economical than using some other option misses the point of how the car works. Practical tests have shown that using CHRG is less economical when the battery is above 60% full. There is a general consensus that using CHRG when in Parallel mode (above 40mph/60kph) is more economical than when in Series mode at lower speeds. And as mentioned, using CHRG for long periods may be very slightly more economical than letting the car charge itself via the Hysteresis Loop.

To be honest, just putting it in 'D' and leaving it to its own devices is not a bad solution unless you enjoy twiddling the settings during a journey. I've not seen any repeatable tests that show if one way is better than another.
2015 GX4hs since 03/18
2015 Renault Zoe R240 owner since 11/17

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zzcoopej
Posts: 278
Joined: Tue Apr 14, 2015 1:57 pm
Location: Gosford, Australia
Contact: Website

Re: Best economy for motorway drive

ThudnBlundr wrote: Mon Jul 19, 2021 11:29 am To be honest, just putting it in 'D' and leaving it to its own devices is not a bad solution unless you enjoy twiddling the settings during a journey. I've not seen any repeatable tests that show if one way is better than another.
If there was a real winner, Mitsubishi would have used it. The only reason you can beat the car is because you have some knowledge of the future of your journey, however even you don't know if accidents or traffic jams will slow you below the parallel hybrid speed.
littlescrote
Posts: 451
Joined: Fri Jul 26, 2019 3:52 am

Re: Best economy for motorway drive

The previous 2 replies are spot on.

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