MME Efficiency: place your bets

timbop

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The question came up in another thread, but I think it deserves its own topic: what's your guess on the final EPA range/efficiency of the Mach E?

** EDIT/NOTE
My mi/kwh numbers are expected driving efficiency displayed on the infotainment system and don't include the overhead in heat loss from charging that EPA includes in their efficiency measurements
**

I'm going to predict:

Route 1 with 18" aero wheels:
3.6 mi/kwh (317 mi range)

Select with 18" non-aero wheels:
3.55 mi/kwh RWD (241 mi range)
3.25 mi/kwh AWD (221 mi range)

Premium/FE with 19" wheels:
3.5 mi/kwh RWD (308 mi range ER, 238 mi range SR)
3.2 mi/kwh AWD (282 mi range ER, 218 mi range SR)
Sponsored

 
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Raymondjram

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The average among small EVs is 4 miles per kWh or 0.9 mJ (mega-Joule) per mile (1 kWh = 3.6 mJ). As an EE, I prefer correct engineering terms. So 3.6 mi/kWh = one mi/mJ. I lke nice round numbers and few digits!
 

FredT

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The question came up in another thread, but I think it deserves its own topic: what's your guess on the final EPA range/efficiency of the Mach E?

I'm going to predict:

Route 1 with 18" aero wheels:
3.6 mi/kwh (317 mi range)

Select with 18" non-aero wheels:
3.55 mi/kwh RWD (241 mi range)
3.25 mi/kwh AWD (221 mi range)

Premium/FE with 19" wheels:
3.5 mi/kwh RWD (308 mi range ER, 238 mi range SR)
3.2 mi/kwh AWD (282 mi range ER, 218 mi range SR)
Too many numbers! I will guess what you said but 2% less, so 276 miles for the AWD ER.

But regarding efficiency, is that what you expect the EPA numbers to be? Because looking at the recent Polestar 2 and XC-40 EPA numbers, I am totally baffled. For the Polestar 2, EPA says 37 kw/100 miles, so 2.7 mi/kwh. That would give a range of 203 miles, but the EPA stated range is 233. Same thing for the XC-40 (and the Tesla Y, for that matter). What am I missing?
 

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The question came up in another thread, but I think it deserves its own topic: what's your guess on the final EPA range/efficiency of the Mach E?

I'm going to predict:

Route 1 with 18" aero wheels:
3.6 mi/kwh (317 mi range)

Select with 18" non-aero wheels:
3.55 mi/kwh RWD (241 mi range)
3.25 mi/kwh AWD (221 mi range)

Premium/FE with 19" wheels:
3.5 mi/kwh RWD (308 mi range ER, 238 mi range SR)
3.2 mi/kwh AWD (282 mi range ER, 218 mi range SR)
I think your Premium/FE estimates are very reasonable. Let's hope the actual figures are slightly better.
 


dbsb3233

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The average among small EVs is 4 miles per kWh or 0.9 mJ (mega-Joule) per mile (1 kWh = 3.6 mJ). As an EE, I prefer correct engineering terms. So 3.6 mi/kWh = one mi/mJ. I lke nice round numbers and few digits!
4 miles/kWh would be fantastic, of course, but x 88 kWh that's 352 miles of range. I would be shocked if that's the EPA combined range. Maybe city (slow speed, lots of regen).

I'll stick with 314 for my EPA RWD ER guess. That's about 3.6.

What I actually care about is the 75 MPH cruising number though. City doesn't matter to me.
 
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timbop

timbop

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For the Polestar 2, EPA says 37 kw/100 miles, so 2.7 mi/kwh. That would give a range of 203 miles, but the EPA stated range is 233. Same thing for the XC-40 (and the Tesla Y, for that matter). What am I missing?
I believe that the kw/100mi number includes the energy lost through heat during the charging process, so you know how much it actually costs to charge the car. The range number is how far you can go after it is fully charged.

My numbers don't account for that extra lost energy
 

dbsb3233

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I believe that the kw/100mi number includes the energy lost through heat during the charging process, so you know how much it actually costs to charge the car. The range number is how far you can go after it is fully charged.

My numbers don't account for that extra lost energy
I don't think those numbers have anything to do with charging though, do they? I can see how that would affect charging times, but once 88 kWh is in the battery (or whatever the number for those models), it should just be about how many miles result from the kWh in the battery.

Or so I would think.
 
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timbop

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I don't think those numbers have anything to do with charging though, do they? I can see how that would affect charging times, but once 88 kWh is in the battery (or whatever the number for those models), it should just be about how many miles result from the kWh in the battery.

Or so I would think.
Right, but EPA measures total energy drawn from the grid, not how much the pack holds. So, using the polestar example it takes 86.2kwh of energy to charge an 80kwh pack, because 6.2kwh is used in the process of charging. That is, to fully charge an 80kwh battery that will go 233 miles we have to use 86.2 kwh of electricity:

233 mi * 37 kwh/100mi = 86.21kwh
so charging gets 233/86.21 = 2.7 mi/kwh

When driving that 80kw will go 233 miles, so you'd see the car report it is getting 2.9 mi/kwh on the road.
 

dbsb3233

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Right, but EPA measures total energy drawn from the grid, not how much the pack holds.
Really??? Wow. I didn't know that.

So that makes the number utterly useless. At least to drivers anyway.
 
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timbop

timbop

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Really??? Wow. I didn't know that.

So that makes the number utterly useless. At least to drivers anyway.
No, that's not true. If you want to know your monthly electricity usage based on the "average" driving model then you do simple multiplication of the kwh/100mi factor by miles and slide the decimal point 2 places left. If you want to know the mi/kwh while driving, you have to do simple division of the "combined range" by the battery size.
 

dbsb3233

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No, that's not true. If you want to know your monthly electricity usage based on the "average" driving model then you do simple multiplication of the kwh/100mi factor by miles and slide the decimal point 2 places left. If you want to know the mi/kwh while driving, you have to do simple division of the "combined range" by the battery size.
Well that's true. I didn't think about it from a fuel cost standpoint, which is something drivers care about. Good point.

But that also creates a confusing disconnect with range, and is just gonna confuse people. As is did here. There's basically conflicting miles/kWh numbers (one for charging purposes and one for driving range purposes). Ugh. As if it won't be confusing enough for people.

One more reason that EPA numbers are just a bad fit for BEVs.
 

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Well that's true. I didn't think about it from a fuel cost standpoint, which is something drivers care about. Good point.

But that also creates a confusing disconnect with range, and is just gonna confuse people. As is did here. There's basically conflicting miles/kWh numbers (one for charging purposes and one for driving range purposes). Ugh. As if it won't be confusing enough for people.

One more reason that EPA numbers are just a bad fit for BEVs.
I'm confused. Hey, why don't we talk about mpge while we're at it! ?
 
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timbop

timbop

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But that also creates a confusing disconnect with range, and is just gonna confuse people.
Definitely. It took me a long time to finally figure out what was going on - today.
 

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I'll guess

Select, Premium Mach E 3.38
Premium, CA Route 1 Mach EX 3.41
FE, Premium Mach E4X 3.41
Sponsored

 
 




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