Motorway efficiency test MG4 Trophy

[Fogey]

Ok, did a couple more test runs today using the same route which produced 3.8ml/kw with regen 1 and 3 at 60 tp 65mph.

There was quite a stiff wind which gave some interesting results when comparing driving with the tailwind v against the headwind.

Test 1: Eco mode, regen 3, target speed 65 to 70mph. Average trip speed 63mph. Over 54 miles the ml/kwh was 3.3, which was quite a drop from the 3.8 achieved at just 5mph less.

Over 27 miles with a 20mph tailwind I achieved 3.9. The return 27 miles into the wind gave only 2.7

Test 2: Eco mode, regen 3, target speed 55-60mph.Average trip speed 52mph. Over 54 miles the ml/kwh was 4.5

Over 27 miles with tailwind I achieved 5.0. The return leg into the wind gave 4.0

It's clear that speed and wind conditions have an outsized impact on efficiency. Perhaps the mg4 isn't the most aerodynamic car around, and the wind noise probably is a symptom of that.

Over the tests we have:

55-60mph: 4.5
60-65mph: 3.8
65-70mph: 3.3

20mph tailwind can add 0.5 to 0.6, 20mph headwind can take away 0.5 to 0.6 depending on driving speed. Clearly wind effect can be much higher, today was only around 20mph average wind.

Thankyou so much for that, Nigel - excellent and valuable info for any prospective buyer.

In a way, the results shouldn't be that surprising, as aerodynamic resistance increases with velocity cubed. Plus unlike an ICE-powered car, the EV's energy efficiency is relatively independent of power setting - the ICE "flatters" high-speed operation because of its gross inefficiency at lower power settings.

But I would imagine the MG4 is pretty aerodynamic - it certainly looks it, and underneath it's pretty smooth. Maybe its battery monitoring is a bit pessimistic?

 

[Nigelleics]

Thankyou so much for that, Nigel - excellent and valuable info for any prospective buyer.

In a way, the results shouldn't be that surprising, as aerodynamic resistance increases with velocity cubed. Plus unlike an ICE-powered car, the EV's energy efficiency is relatively independent of power setting - the ICE "flatters" high-speed operation because of its gross inefficiency at lower power settings.

But I would imagine the MG4 is pretty aerodynamic - it certainly looks it, and underneath it's pretty smooth. Maybe its battery monitoring is a bit pessimistic?

I should add that compared to my first 2 tests, I did have another adult and child in the car this time, so possibly you could add 0.1 to all the most recent figures in comparison with the prior test. I think the total weight of car increased by 5%.

I'm looking at this from a cold accounting point of view un that I'm looking for cheap motoring. It's useful to know that 4ml/kwh can be achieved at 55-60 into a headwind and at 65-70 with a tailwind, and almost at 60-65 regardless. At grid cost of 33p, this gives a per mile cost of 8p versus 17p with diesel, cutting £900 a year off the cost of 10k annual miles. With solar the savings are practically doubled.

 

[Fogey]

I'm looking at this from a cold accounting point of view un that I'm looking for cheap motoring. It's useful to know that 4ml/kwh can be achieved at 55-60 into a headwind and at 65-70 with a tailwind, and almost at 60-65 regardless. At grid cost of 33p, this gives a per mile cost of 8p versus 17p with diesel, cutting £900 a year off the cost of 10k annual miles. With solar the savings are practically doubled.

I'm the opposite - range is key for me!

 

[Nigelleics]

I'm the opposite - range is key for me!

Extra range = extra savings. I'm just thinking that blasting down to the South of France could be out unless I'm willing to spend half my time charging

 

[Big Al]

I should add that compared to my first 2 tests, I did have another adult and child in the car this time, so possibly you could add 0.1 to all the most recent figures in comparison with the prior test. I think the total weight of car increased by 5%.

I'm looking at this from a cold accounting point of view un that I'm looking for cheap motoring. It's useful to know that 4ml/kwh can be achieved at 55-60 into a headwind and at 65-70 with a tailwind, and almost at 60-65 regardless. At grid cost of 33p, this gives a per mile cost of 8p versus 17p with diesel, cutting £900 a year off the cost of 10k annual miles. With solar the savings are practically doubled.

Part of the EV puzzle is to charge the car on a cheap rate. A standard economy 7 tariff will get your price per mile to 4p or less. And you've a 7 hour window to charge the car

 

[JayEV2022]

Ok, did a couple more test runs today using the same route which produced 3.8ml/kw with regen 1 and 3 at 60 tp 65mph.

There was quite a stiff wind which gave some interesting results when comparing driving with the tailwind v against the headwind.

Test 1: Eco mode, regen 3, target speed 65 to 70mph. Average trip speed 63mph. Over 54 miles the ml/kwh was 3.3, which was quite a drop from the 3.8 achieved at just 5mph less.

Over 27 miles with a 20mph tailwind I achieved 3.9. The return 27 miles into the wind gave only 2.7

Test 2: Eco mode, regen 3, target speed 55-60mph.Average trip speed 52mph. Over 54 miles the ml/kwh was 4.5

Over 27 miles with tailwind I achieved 5.0. The return leg into the wind gave 4.0

It's clear that speed and wind conditions have an outsized impact on efficiency. Perhaps the mg4 isn't the most aerodynamic car around, and the wind noise probably is a symptom of that.

Over the tests we have:

55-60mph: 4.5
60-65mph: 3.8
65-70mph: 3.3

20mph tailwind can add 0.5 to 0.6, 20mph headwind can take away 0.5 to 0.6 depending on driving speed. Clearly wind effect can be much higher, today was only around 20mph average wind.

Now these are the tests I am looking for... thanks alot... were you using the heater at all or heated seats etc. Are you planning to do anymore. Thanks for the tests so far!

 

[Nigelleics]

Now these are the tests I am looking for... thanks alot... were you using the heater at all or heated seats etc. Are you planning to do anymore. Thanks for the tests so far!

No ac, no heating. What other tests are you interested in?

 

[Ian Key]

Part of the EV puzzle is to charge the car on a cheap rate. A standard economy 7 tariff will get your price per mile to 4p or less. And you've a 7 hour window to charge the car

I agree. My Economy 7 tariff is 13.88p/kWh which assuming that a full charge gives you 61.7kWh of usable battery and a WLTP range of 270 for the Trophy is 3.2p per mile.
Even better if you are just going to the shops and back etc. which works out at 2.4p per mile.
My 10 year old 2 litre diesel is costing me 24p per mile.

 

[JayEV2022]

No ac, no heating. What other tests are you interested in?

Morning Nigel, thanks for the extra info. I will be doing a frequent run from Leicester to London and then back hopefuly without charging in between. I will be doing this every 1 or 2 weeks when I get my MG4 SE Long range. Each way it is a around 97 miles, 89 miles on the M1 and the remaining 8 miles on 40mph roads. I want to comfortably do a round trip there and back. I am looking to really take advantage of regen on slightly steep downhills.

Did you have mg polit on any of your runs. The reason why I ask is because I don't think regen works with MG polit or something along those lines. Having said that if I do not use mg pilot I might be able to increase my regen to benefit my range that little bit more.

Many thanks for all your help so far

 

[Big Al]

Morning Nigel, thanks for the extra info. I will be doing a frequent run from Leicester to London and then back hopefuly without charging in between. I will be doing this every 1 or 2 weeks when I get my MG4 SE Long range. Each way it is a around 97 miles, 89 miles on the M1 and the remaining 8 miles on 40mph roads. I want to comfortably do a round trip there and back. I am looking to really take advantage of regen on slightly steep downhills.

Did you have mg polit on any of your runs. The reason why I ask is because I don't think regen works with MG polit or something along those lines. Having said that if I do not use mg pilot I might be able to increase my regen to benefit my range that little bit more.

Many thanks for all your help so far

MG Pilot uses regen for braking, I see -18 figures on the power meter. It also uses the brakes if it has to, ie someone pulls in front of you with no gap.

 

[JayEV2022]

MG Pilot uses regen for braking, I see -18 figures on the power meter. It also uses the brakes if it has to, ie someone pulls in front of you with no gap.

Oh it does, thanks for confirming... I am not sure where I got that from then haa. How is the lane assist, do you have to guide the steering wheel often or does it pretty much do a good job.

 

[beefyj]

I’ve seen that removing lane assist or TJA type controls in other EVs helps with efficiency. Any powered assistance has to take the energy from somewhere I guess, but wouldn’t have thought it was hugely significant unless on a very efficient car.

Still getting 1p/mile in the Ioniq 38 as it averages 5+ miles/kWh everywhere. (And I’m still in GO 5p/kWh till March).

Update on our MG4 to be posted in the oil leak thread soon, either later today or tomorrow.

 

[wiz043]

I am sorry if this has been answered before but when you enable MG Pilot in standby on the screen and later switch to it on the steering wheel does that automatically enable LKA and TJA or can you enable them separately to start with?
When I restart the car I would like to have MG Pilot/ACC enabled and possibly TJA but not LKA. Can that be done or do I have to disable LKA each time?

 

[Fogey]

It occurs to me that this thread is quite illuminating, the main point being that, as far as EVs are concerned (i.e. where range is critical), an airspeed indicator would be a very useful addition. Given that, at motorway speeds, aero resistance is dominant. A bit tricky to diy though...

But at least it would enable the driver to modulate speed as appropriate, on longer journeys.

I suppose the alternative is to keep an eye on the power meter, which could be "calibrated" versus various road speeds in calm conditions. That way, it ought to be possible to deduce air speed, and therefore projected range.

I have to say though, I'm starting to have second thoughts about the wisdom of my forthcoming purchase, which would require a real-world range somewhat greater than half the headline 280 miles of the SE/LR. (And that's one-way, which could be into a headwind all the way).

 

[Nigelleics]

It occurs to me that this thread is quite illuminating, the main point being that, as far as EVs are concerned (i.e. where range is critical), an airspeed indicator would be a very useful addition. Given that, at motorway speeds, aero resistance is dominant. A bit tricky to diy though...

But at least it would enable the driver to modulate speed as appropriate, on longer journeys.

I suppose the alternative is to keep an eye on the power meter, which could be "calibrated" versus various road speeds in calm conditions. That way, it ought to be possible to deduce air speed, and therefore projected range.

I have to say though, I'm starting to have second thoughts about the wisdom of my forthcoming purchase, which would require a real-world range somewhat greater than half the headline 280 miles of the SE/LR. (And that's one-way, which could be into a headwind all the way).

The route I use gave almost ideal conditions to gauge the effect of headwind, as it's the A46 'old fosse way' therefore very straight and orientated SW to NE with a strong SW'ly on the day.

In spite of this I still managed to get 4.0 at lorry speeds, and without the extra weight in the car I'd probably have got 4.1, which would give almost 250 miles range.

With sensing the wind strength, I'd just check a weather app for wind speed and direction. If the average wind speed is 15mph or below I'd expect the impact to be far more minimal. Away from the North and West these days aren't too frequent.

 

[siteguru]

I have to say though, I'm starting to have second thoughts about the wisdom of my forthcoming purchase, which would require a real-world range somewhat greater than half the headline 280 miles of the SE/LR. (And that's one-way, which could be into a headwind all the way).

But how often would you need to do that journey? And if the mileage is, say, 180 miles each way, do you have charging capabilities at the destination?

Edit: and for such a long journey you should be taking a break anyway ... 15 mins at a rapid charger should assuage any range anxieties.

 

[Fogey]

The route I use gave almost ideal conditions to gauge the effect of headwind, as it's the A46 'old fosse way' therefore very straight and orientated SW to NE with a strong SW'ly on the day.

In spite of this I still managed to get 4.0 at lorry speeds, and without the extra weight in the car I'd probably have got 4.1, which would give almost 250 miles range.

With sensing the wind strength, I'd just check a weather app for wind speed and direction. If the average wind speed is 15mph or below I'd expect the impact to be far more minimal. Away from the North and West these days aren't too frequent.

Well, it's the 2.7m/kWh which worries me - given that it's only 20mph headwind. I shall have to think about this...

 

[Fogey]

But how often would you need to do that journey? And if the mileage is, say, 180 miles each way, do you have charging capabilities at the destination?

The thing is, I wouldn't want to be constrained to avoiding the journey when it's too windy, but, yes, it's only one way, and there'll be charging to 100% as required at the destination. But I do want to avoid having to a) worry and b) search around for a top-up en-route.

Edit: It's "only" 150 miles or so, by the way.

 

[siteguru]

I was being deliberately pessimistic.

The SE LR has a 61.7kWh usable battery - let's call it 60 for easy maths. It's recommended to avoid going below 10% charge if you can help it, so let's call that 54kWh normally usable. 2.7 miles per kWh would give a range of 146 miles. If you stretch down to 5% charge that would give you a further 8 miles, so 154 miles, with still a further buffer.

These are overly pessimistic calculations - even just 3 miles per kWh and those change to 162 miles and 171 miles. And I'd anticipate getting even better than that.

 

[colsky]

I was being deliberately pessimistic.

The SE LR has a 61.7kWh usable battery - let's call it 60 for easy maths. It's recommended to avoid going below 10% charge if you can help it, so let's call that 54kWh normally usable. 2.7 miles per kWh would give a range of 146 miles. If you stretch down to 5% charge that would give you a further 8 miles, so 154 miles, with still a further buffer.

These are overly pessimistic calculations - even just 3 miles per kWh and those change to 162 miles and 171 miles. And I'd anticipate getting even better than that.

Excuse my ignorance, but is it recommended to avoid going below 10%, or is it recommended to avoid leaving it at below 10%? So, say, you can do a long trip and take it down to 5%, but just make sure you charge soon after. Otherwise, the stated range capability is wrong. I was told that in my ZS there was an unseen buffer below 0%.