Fuel economy and how to save fuel. What can we agree on.?

[Trex]

Hi folks,

Now these are my opinions.

How best to save fuel:

1. Try to be in Ev mode as much as possible.

2. Avoid slow speed series mode as much as possible. Mitsubishi put that lock-up clutch in the transmission for a reason and it is NOT to make the Phev simpler or cheaper.

3. Do not use the heater on certain models of the phev.

4. Keep your tyres inflated to the recommended pressure.

5. Faster speeds use more fuel. Parallel or slow speed series mode.

6. This is a big one. Clean out your Phev now and again. Just did mine and my wife was carrying chairs and umbrellas and eskies for soccer games that finished over 2 months ago :shock:
Probably 150kg of stuff. That's worth a bit of fuel for sure. :lol:

Can we agree on these points?

Have I missed any that we can agree on?

Please ask questions if you do not understand what I have written. Or tell me why if you do not agree.

Regards Trex.

 

[anko]

Regarding #1: Shouldn't that be "Use grid power as much as possible"?

Regarding#2 + #5: When comparing 39 mph in serial mode to 40 mph in parallel mode, I would think you would be right. (Although we must not forget that serial mode allows the motor management to play with rpm and torque to achieve optimal efficiency, more than parallel mode with its fixed rpm does.) But when comparing 39 mph to (e.g.) 50 mph, it could be that the increased drag nullifies the advantage of not having to convert power twice.

 

[Trex]

Regarding #1: Shouldn't that be "Use grid power as much as possible"?

Regarding#2 + #5: When comparing 39 mph in serial mode to 40 mph in parallel mode, I would think you would be right. (Although we must not forget that serial mode allows the motor management to play with rpm and torque to achieve optimal efficiency, more than parallel mode with its fixed rpm does.) But when comparing 39 mph to (e.g.) 50 mph, it could be that the increased drag nullifies the advantage of not having to convert power twice.

anko I would think that the highest % ev whether it comes from the grid or the petrol motor would be best for saving fuel. Do you not agree?

Have changed No 5. and added No 6. just before I read your post.

Do you not agree to avoid series mode (No 2.) for best savings of fuel. Why? You saw the other day how I got a 6.7L/100k in a 60kph zone (series mode) and you saw how Mitsubishi got 6.5L/100k at 92kph. I just did a test the other night at 80kph (in a 90kph zone) and got a 6.4l/100k in one direction and 6L/100k in the other direction. Still tells me to avoid series mode.

Or do agree with No 5. the way I have written it now?

Regards Trex.

 

[Neverfuel]

I would also add:

Use Eco mode
Use cruise control or ACC if you have it
Use the speed limiter
Maximise your EV range by using regen and coasting where appropriate

 

[Trex]

I would also add:

Use Eco mode
Use cruise control or ACC if you have it
Use the speed limiter
Maximise your EV range by using regen and coasting where appropriate

Thanks for your input Neverfuel

I will put them in points 7- 10

How best to save fuel:

1. Try to be in Ev mode as much as possible.

2. Avoid slow speed series mode as much as possible.

3. Do not use the heater on certain models of the phev.

4. Keep your tyres inflated to the recommended pressure.

5. Faster speeds use more fuel. Parallel or slow speed series mode.

6. Do not carry around excess weight not needed for the trip.

7. Use Eco mode

8. Use cruise control or ACC if you have it

9. Use the speed limiter

10. Maximise your EV range by using regen and coasting where appropriate

Can we agree on these points?

Have we missed any that we can agree on?

Regards Trex.

 

[Neverfuel]

Contentious one Trex depending where you live but:

Use electricity that you don't have to pay for (eg hotel charging points, employers etc). However, follow the rules to the letter if fast charging ( but do this as well ).

 

[Trex]

Contentious one Trex depending where you live but:

Use electricity that you don't have to pay for (eg hotel charging points, employers etc). However, follow the rules to the letter if fast charging ( but do this as well ).

Hi Neverfuel. (I just love your avatar) :lol:

There is probably a few contentious ones here. For example No 3. Do not use the heater on certain models of the phev that I put there. You could probably say that on extended trips away where you are going to run the petrol motor anyway turning on the heat will not cost any fuel. I probably should pull that one out. What do you think?

Regards Trex.

 

[Neverfuel]

Contentious one Trex depending where you live but:

Use electricity that you don't have to pay for (eg hotel charging points, employers etc). However, follow the rules to the letter if fast charging ( but do this as well ).

Hi Neverfuel. (I just love your avatar) :lol:

There is probably a few contentious ones here. For example No 3. Do not use the heater on certain models of the phev that I put there. You could probably say that on extended trips away where you are going to run the petrol motor anyway turning on the heat will not cost any fuel. I probably should pull that one out. What do you think?

Regards Trex.

Maybe "Limit the use of the heater...." Sounds better.

 

[anko]

anko I would think that the highest % ev whether it comes from the grid or the petrol motor would be best for saving fuel. Do you not agree?

I do agree. But where "using GRID power as much a s possible" is something you have control over, "driving EV as much as possible" is more a result of the proper strategy than a strategy by itself. I mean, how do you achieve that?

Do you not agree to avoid series mode (No 2.) for best savings of fuel. Why? You saw the other day how I got a 6.7L/100k in a 60kph zone (series mode) and you saw how Mitsubishi got 6.5L/100k at 92kph. I just did a test the other night at 80kph (in a 90kph zone) and got a 6.4l/100k in one direction and 6L/100k in the other direction. Still tells me to avoid series mode.

If I was driving 38 MPH in serial mode and was able to speed up to 42 MPH in order to get into parallel mode, I would do so. But, despite there promising numbers you present, I would not drive 60 MPH in stead of 38 MPH, hoping to save fuel. Gut feeling. On the other hand, when will you ever be in a situation that you can choose between driving 38 MPH vs 60 MPH without either speeding or annoying other traffic?

Or do agree with No 5. the way I have written it now?

Sure.

 

[anko]

Contentious one Trex depending where you live but:

Use electricity that you don't have to pay for (eg hotel charging points, employers etc). However, follow the rules to the letter if fast charging ( but do this as well ).

As this kind of electricity is by definition GRID electricity, I would agree (per my first response to this topic). But the fact that this electricity is free does not increase fuel economy or save fuel :ugeek:

 

[gwatpe]

anko I would think that the highest % ev whether it comes from the grid or the petrol motor would be best for saving fuel. Do you not agree?

I do agree. But where "using GRID power as much a s possible" is something you have control over, "driving EV as much as possible" is more a result of the proper strategy than a strategy by itself. I mean, how do you achieve that?

I had been trying to put words to paper in a similar way but +1 to "anko" for pipping me at the post.

 

[Neverfuel]

Contentious one Trex depending where you live but:

Use electricity that you don't have to pay for (eg hotel charging points, employers etc). However, follow the rules to the letter if fast charging ( but do this as well ).

As this kind of electricity is by definition GRID electricity, I would agree (per my first response to this topic). But the fact that this electricity is free does not increase fuel economy or save fuel :ugeek:

I suppose it depends how you interpret "saving fuel". On a long journey I can choose to fast charge once or more during the trip. Any mileage I do on that charge is mileage I no longer need to use fuel for. Similarly I can choose to continue my journey without charging en route at the expense of the mpg figures.

I am just preparing a 6 month write up and talk about some of the experiments I did when I first got the car - I will be posting it at the end of next week.

 

[Neverfuel]

Hi Trex

Point five looks to contradict point 2 - perhaps just needs rewording.

 

[Trex]

Hi folks and thanks for the input.

How about this?

How to save Fuel:

1. Try to be in Ev mode as much as possible. Use the grid charge as much as possible and when accelerating try to keep the petrol motor off.

2. Avoid slow speed series mode as much as possible. Ie use your SOC around slower areas.

3. Avoid using the heater especially on certain models of the phev unless the petrol motor was going to run anyway because of length of trip.

4. Keep your tyres inflated to the recommended pressure.

5. Faster speeds use more fuel. Parallel or slow speed series mode but see No 2.

6. Do not carry around excess weight not needed for the trip.

7. Use Eco mode

8. Use cruise control or ACC if you have it

9. Use the speed limiter

10. Maximise your EV range by using regen and coasting where appropriate

Can we agree on these points?

Have we missed any that we can agree on?

If someone can help with wording. I probably need it .

Regards Trex.

 

[Ozukus]

Can we agree on these points?

Have we missed any that we can agree on?

If someone can help with wording. I probably need it .

Regards Trex.

You forgot point 11

11. Don't let the other half drive the car, who won't execute points 1-10 unless by accident :?

 

[maby]

...

I suppose it depends how you interpret "saving fuel". On a long journey I can choose to fast charge once or more during the trip. Any mileage I do on that charge is mileage I no longer need to use fuel for. Similarly I can choose to continue my journey without charging en route at the expense of the mpg figures.

I am just preparing a 6 month write up and talk about some of the experiments I did when I first got the car - I will be posting it at the end of next week.

You also have to consider the entire journey profile in order to select the best strategy. I think the jury is still out on anko's suggestion that it is more efficient on long runs to let the battery go flat early, but even if he is right, the improved efficiency while running on petrol would have to more than compensate for the reduced EV range if the start of your journey was all at motorway speeds. If running on a flat battery on petrol returns 2mpg better than pressing save and running on petrol with a fully charged battery, you would have to burn at least 5 gallons to make up for the potential 10 miles of EV range that you could lose by letting the battery discharge driving the car at fast motorway speeds.

 

[anko]

..., but even if he is right, the improved efficiency while running on petrol would have to more than compensate for the reduced EV range if the start of your journey was all at motorway speeds. If running on a flat battery on petrol returns 2mpg better than pressing save and running on petrol with a fully charged battery, you would have to burn at least 5 gallons to make up for the potential 10 miles of EV range that you could lose by letting the battery discharge driving the car at fast motorway speeds.

But that is the whole point. There is no reduced EV range . At the end, when we exit the motorway, we have the same amount of change (or EV range) in the battery. The only difference is that rather then spending battery power at the end (as you do it), I spent it at the beginning. Resulting join an overall lower average SOC.

 

[maby]

..., but even if he is right, the improved efficiency while running on petrol would have to more than compensate for the reduced EV range if the start of your journey was all at motorway speeds. If running on a flat battery on petrol returns 2mpg better than pressing save and running on petrol with a fully charged battery, you would have to burn at least 5 gallons to make up for the potential 10 miles of EV range that you could lose by letting the battery discharge driving the car at fast motorway speeds.

But that is the whole point. There is no reduced EV range . At the end, when we exit the motorway, we have the same amount of change (or EV range) in the battery. The only difference is that rather then spending battery power at the end (as you do it), I spent it at the beginning. Resulting join an overall lower average SOC.

So are you suggesting that the EV range achieved is independent of speed? That certainly is not my experience. I reckon on getting around 25 miles on a full battery at 30mph on urban roads, but under 20 miles at 60 to 70mph on a motorway. If I use up my charge at the start of the journey, getting five or ten miles less range because I've used it to propel me at 70mph, then the improved fuel consumption running on petrol with a flat battery has got to make up for that lost range up before it can contribute anything to reduced overall running costs, hasn't it?

 

[anko]

So are you suggesting that the EV range achieved is independent of speed?

No, that is totally not what I am suggesting :shock: .

I am just saying that if we both enter the motorway with e.g. 90% SOC and leave with 40% SOC, we have spent the same amount of electricity on the motorway. The fact that, between entering and exiting the motorway, your SOC has stayed high and dropped towards the end and mine dropped to 30 and crawled back up towards the end doesn't change that.

When you hit the Save button on the motorway, the engine is switched off a certain amount of the time, right? During those periods you are using electricity or in other words spending EV range..... I think I need to draw a picture .....

 

[maby]

So are you suggesting that the EV range achieved is independent of speed?

No, that is totally not what I am suggesting :shock: .

I am just saying that if we both enter the motorway with e.g. 90% SOC and leave with 40% SOC, we have spent the same amount of electricity on the motorway. The fact that, between entering and exiting the motorway, your SOC has stayed high and dropped towards the end and mine dropped to 30 and crawled back up towards the end doesn't change that.

When you hit the Save button on the motorway, the engine is switched off a certain amount of the time, right? During those periods you are using electricity or in other words spending EV range..... I think I need to draw a picture .....

No need for pictures - we are simply talking about different scenarios - and my original post was suggesting that the strategy for minimising running costs must look at the entire journey profile, not individual segments in isolation. Your simplistic view above only applies to journeys that are 100% motorway, or close to it, and relatively short. Under those circumstances, there may be some small benefit overall from using up the charge early. A more common scenario would be someone leaving their house, joining a motorway nearby, driving several tens of miles (possibly more) on the motorway and then finishing off their journey on urban roads - that applies to the vast majority of people commuting into London, for example. My battery is going to give me a lot more range on London roads at 20 to 30mph (completely ignoring any environmental considerations). For that journey profile, you are not going to suggest using your charge up on the motorway and then driving in London on petrol, are you?

As far as the second point is concerned, there's a big difference between using EV range gained from the grid charge and the alternation between on engine and running on battery that you get in serial hybrid on a flat battery. The former is much more economical and ecological since it is consuming power that was purchased off the grid at relatively low prices and generated through a mixture of fuels which includes renewables and nuclear. The latter is just burning petrol slightly more efficiently than a conventional 2 litre car of similar size would.