Grungy
Posts: 2
Joined: Tue Dec 20, 2022 5:54 pm

Fuel economy at highway speed phev vs ice model

Good day all,
I'm new here and posting my first post. I have searched all through the tech section and could not find the answer so here it goes. I am getting a 2023 Outlander PHEV in the first week of January. I can tell the vast majority of users here really like their Outlanders.

When comparing the highway fuel economy between the ICE version of the Outlander and the PHEV version, I was surprised to see the ICE version was more efficient. I was trained as an Engineer in 1990 but became a pilot and have not used my engineering degree since graduation. So I understand some physics but am by no means current.
It's my understanding that air resistance and therefore body style is the main determining factor for how much energy is needed to keep the can going at highway speed. Both versions of those Outlanders have the same body style and chassis. Both have the same engine except the ICE version has a slightly higher compression ratio and operates on the conventional Otto cycle. The PHEV operates on the more efficient Atkinson cycle. Sure the PHEV is heavier but with the Atkinson cycle and the direct drive to the front wheels in parallel mode without a transmission should be more efficient. The only thing I can think of is the efficiency losses as you generate electricity for the batteries and the efficiency losses as you use the energy put back in the batteries as the engine cycles on and off. 2023 Outlander ICE gets 7.9 litres per 100km, PHEV gets 8.7.
Interesting the Toyota RAV 4 PHEV gets better highway fuel economy than the ICE version and regular Hybrid is better than both. Rav 4 PHEV 6.4 l/100km, Rav 4 Hybrid 6.3, Rav 4 ICE 6.9. All three Rav4s have the same engine and they all have transmissions. How can the Rav4s with batteries and motors and extra weight get better fuel economy than the ICE but the Outlander can't?
So is the testing cycle forcing the Outlander in series mode sometimes? To my knowledge, Canada uses the same cycle as the USA EPA uses.

For real life, I really only care about steady 105 kmh or 115 kmh fuel economy. The city numbers don't matter to me because I will be using the battery and electric motors then. Does Toyota have it right with their mechanical set up or does Mitsubishi have it right? Again, I would think the Mitsubishi set up should do better. I initially had put my name on a list for a Rav 4 as its ev range is 68 km. It's 58 km round trip for us to go to town for errands. Before 2023, the Outlander didn't have the ev range we needed. After being on the Rav4 list for 15 months and them being told I would have to wait at least 6 more months, I put myself on the wait list for the 2023 Outlander with the 20 kwh battery and 61km ev range. It's a 70 to 80 kmh road to town so I expect to get much more range than the 61 advertised.

We mostly stay local but we also do some highway trips so I am still interested in highway fuel economy. The Rav 4 gets better mileage but I don't know how long I would have to wait. I'm currently driving an ICE car that gets 7.1 highway.

Anyone have real world highway fuel numbers on the 2023 Outlander PHEV (it has a larger body and chassis)?

Andrew
AndyInOz
Posts: 728
Joined: Wed Sep 09, 2015 5:05 pm
Location: Australia

Re: Fuel economy at highway speed phev vs ice model

Just a random thought, make sure that you're not comparing a Diesel Outlander with a Petrol Outlander.

Otherwise, my guess would be under-inflation of the tyres on the PHEV.

According to the company that sold me my tyres, the manufacturers recommendation of 38 psi was too low, and they were able to demonstrate that my previous tyres had 'under-inflation' wear pattern.

They recommended 41 psi.

If the two Outlanders had identical tyre pressures for the measurement runs, that would explain the poor results for the heavier vehicle.

I note that you're considering a difference of less than one litre of fuel per 100 kilometres...
2014 PHEV Aspire, Arctic Silver;
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nrayanov
Posts: 51
Joined: Sun Oct 16, 2022 1:59 pm

Re: Fuel economy at highway speed phev vs ice model

Grungy wrote: Thu Dec 22, 2022 5:17 pm It's my understanding that air resistance and therefore body style is the main determining factor for how much energy is needed to keep the can going at highway speed.
Andrew
What you are missing is the mass. The PHEV is heavier because of the batteries.
Grungy
Posts: 2
Joined: Tue Dec 20, 2022 5:54 pm

Re: Fuel economy at highway speed phev vs ice model

Good point if the tires are under inflated. Interesting that Mitsubishi could not figure out what the proper tire pressure should be.

As far as the PHEV being heavier, that should not effect highway fuel economy that much. The Toyota Rav4 PHEV is heavier than the ICE Rav4 but it gets better fuel economy. So I don't think the weight is the reason why.

Grungy
motco
Posts: 2
Joined: Thu Nov 17, 2022 7:48 am

Re: Fuel economy at highway speed phev vs ice model

Weight (mass) is pertinent when accelerating or hill climbing, of course, and it may affect rolling resistance. The last factor is largely dealt with by higher tyre pressures. It's an education to one such as myself whose driving life has hitherto been exclusively ICE just how much weather and speed can affect economy. I already knew that wet roads cause higher consumption, and headwinds likewise, but some diesel cars (I've had four) are at their most economical at the upper end of legality - 60mph or thereabouts. My diesel Jaguar X-Type is barely above idle in 6th gear at 60mph. An EV is consuming energy in handfuls at higher speeds though.

EVs are very seriously affected by cold weather and 'hotel loading' - i.e. heater/aircon, lights and wipers. The heater being head and shoulders worse than any other. Driving style is, I find, gentler in an auto and more so still in an EV than it is in a manual. I'm constantly striving to reach the speed of the next upward gear change in a manual.
Outlander Dynamic MY2020, BMW Z3 Sport Roadster 2002 build 2.2i straight six, Westfield SEiW 2 litre (for trackday use). Jaguar X-Type Sovereign Estate leaving soon. Nissan leaf Tekna already left!
nrayanov
Posts: 51
Joined: Sun Oct 16, 2022 1:59 pm

Re: Fuel economy at highway speed phev vs ice model

Grungy wrote: Fri Dec 23, 2022 5:10 pm As far as the PHEV being heavier, that should not effect highway fuel economy that much. The Toyota Rav4 PHEV is heavier than the ICE Rav4 but it gets better fuel economy. So I don't think the weight is the reason why.
Grungy
It's true that the Mitsubishi Outlander PHEV does have a lower fuel economy rating than some other PHEV SUVs, such as the Toyota Rav4 Prime. However, it's important to keep in mind that the Outlander PHEV has significantly better all-wheel drive (AWD) capabilities.

See more here: https://www.myoutlanderphev.com/forum/v ... 374#p60374
Hasenphever
Posts: 13
Joined: Wed Jan 04, 2023 8:44 am

Re: Fuel economy at highway speed phev vs ice model

Based on my limited experience with the 2023 PHEV, I wonder if it has to do with the design of the system where the ICE charges the battery in non-demanding situations, rather than directly propelling a transmission or axle? There is no setting that I know of to prevent the ICE from charging the battery. Even when the battery is 100% and Save mode is selected, I think the battery is drained to the Save level (as best as it can, it will still use some battery even at 100%) and then charged back to that level by the ICE. Whereas in the RAV4 PRIME, I believe HV mode is only hybrd and the ICE does not charge the battery. I believe there is a Charge mode to do that on the RAV4, but it is not default like it is on the Outlander.

So I wonder if the difference in approach to EV charging vs hybrid driving contributes to the fuel economy differences between the PHEV and hybrid model from each manufacturer?
Last edited by Hasenphever on Sun Jan 15, 2023 11:26 am, edited 1 time in total.
kpetrov
Posts: 185
Joined: Thu Oct 29, 2020 8:59 am

Re: Fuel economy at highway speed phev vs ice model

Hasenphever wrote: Sun Jan 15, 2023 11:11 am Based on my limited experience with the 2023 PHEV, I wonder if it has to do with the design of the system where the ICE charges the battery in non-demanding situations, rather than directly propelling a transmission or axle? There is no setting that I know of to prevent the ICE from charging the battery. Even when the battery is 100% and Save mode is selected, I think the battery is drained to the Save level (as best as it can, it will still use some battery even at 100%) and then charged back to that level by the ICE. Whereas in the RAV4 PRIME, I believe HV mode is only hybrd and the ICE does not charge the battery. I believe there is a Charge mode to do that on the RAV4, but it is not default like it is on the Outlander.

So I wonder if the difference in approach to EV charging vs hybrid driving contributes to the fuel economy differences between the PHEV and hybrid model from each manufacturer?
First of all there is no point to use Save or Charge before your battery drops. Battery won't be charged by the ICE over 80% anyway.
There isn't a setting to prevent ICE charging the battery cause there is no transmission and the ICE should be used in a most efficient way possible at required for the speed rpm's? Outlander PHEV's most efficient way is to use the ICE is for propelling the vehicle and using excess available power to charge the battery where in RAV4 Prime the transmission can use the ICE on highway in more efficient rpm's without charging the battery.
2018 Outlander PHEV (Canadian)
Hasenphever
Posts: 13
Joined: Wed Jan 04, 2023 8:44 am

Re: Fuel economy at highway speed phev vs ice model

kpetrov wrote: Mon Jan 16, 2023 8:57 am
First of all there is no point to use Save or Charge before your battery drops. Battery won't be charged by the ICE over 80% anyway.
There isn't a setting to prevent ICE charging the battery cause there is no transmission and the ICE should be used in a most efficient way possible at required for the speed rpm's? Outlander PHEV's most efficient way is to use the ICE is for propelling the vehicle and using excess available power to charge the battery where in RAV4 Prime the transmission can use the ICE on highway in more efficient rpm's without charging the battery.
So, the crux of the difference between an Outlander PHEV vs Outlander gas and the Rav4 PHEV vs Rav4 gas is really the lack of a transmission in the Outlander PHEV?
kpetrov
Posts: 185
Joined: Thu Oct 29, 2020 8:59 am

Re: Fuel economy at highway speed phev vs ice model

I believe so, but the lack of transition increases the reliability and reduces the price.
I got it for that reason and Prime unavailability. All my daily trips are in battery range, occasional long ones with fuel economy equal to conventional vehicle.
2018 Outlander PHEV (Canadian)

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