[Speculation] Model 3 0.237 kwh/mile!

[MorrisonHiker]

That is not true:
Take a look at Model S 60 vs 85 for proof.
View attachment 238068
Weight matters a lot a low speeds, less so at highway speeds, but it still matters. That's why Model S is not very efficient. It's super heavy

Later years are much better with the S 90D rated at 104 combined, 102 city and 107 highway. I would say that's pretty good for such a heavy car. The lighter S60D is actually rated at only 101 city. Interesting how the S75D is rated 103/102/105 and it's the same car/battery as the S60D...or maybe that's the new battery/motor combination that we've seen the codes for.

 

[mrongey]

Didn't they completely redesign the drive train for the model 3? That, combined with a lighter car and possibly new battery chemistry, could give us these numbers.

It's funny, I was just talking to my dad last night about charging options, since my condo HOA won't let me put a 240v circuit in my garage, and I was speculating about the possibility that the model 3 might have more efficient charging.

 

[EchoDelta]

Okay, so the code is in this URL:

It would have to imply a rather small cross section compared to the S. No other way around it. Like, 86% of the height and 86% of the width, for example. Or a bit larger than that at the widest points, but rounder than the S in cross section. Either that or they got the Cd lower than 0,21, but even getting to 0,21 would be amazing for a rather conventional-looking sedan. Maybe if they were ducting air to the back to fill in the wake, but for a sedan you'd need a pretty significant amount of air...

As much as I like getting down to the physics, I think there we are reading too much into a number plugged in by website people to display savings used for folks to get a first gut impression of the cost of the car. That number (the one typed in the JS, not just the 'real' one it's representing) is a very important number for marketing.

I would...
- get a Model S and X Wh/mi from most 'official' source or computed from the most official source possible. This forum should be able to approximate that.
- Contrast that with the numbers in the website.
- Establish a couple of hypothesis of heuristics/logic/pressure at play.. (have a nice round "savings" number? have an after savings hit just below a round number eg 74,950 ? )
- then see if , by applying that heuristic in reverse , come up with a reverse engineered wH/mi.

And if the Tesla web dev is reading this forum, and you think we're chasing rabbits, please drop us a 'shibboleet' comment of sorts in the html/js.

 

[EchoDelta]

Regardless of ^^ , assuming it is ballpark close, it is still an impressive increase in efficiency.

 

[WarpedOne]

Or a major advance in motor/inverter technology

There is not much room left, they are already over 90% efficient on average.
Even if one could make a motor/inverter with absolutely no losses (100% efficiency), the range would improve by mere 11%.

 

[kevin457]

There is not much room left, they are already over 90% efficient on average.
Even if one could make a motor/inverter with absolutely no losses (100% efficiency), the range would improve by mere 11%.

efficiency as you are describing it means % of power delivered through battery-inverter-motor-wheels. efficiency stated as wh/mi is energy it takes to go a distance. second one is dependent on weight you are rolling on flexible tires.

and I think Tesla's site is using their estimate of an average driver in the savings calculation, including the energy loss from charging, not EPA rating. between the S, and X, you should be able to extrapolate that to the 3, right?

 

[AWDtsla]

But that would mean that .237kWh/mile includes charging losses as well - and that is too good to be true... Something does not add up here

Model S/X losing several hundred watts in overhead while charging, not including the efficiency of the charging electronics. It's about time they fixed that, hopefully they did with the Model 3 hardware. No reason the CID should take more than a few watts to run, definitely not 300.

As for the claimed efficiency of 237, I computed a similar figure a long time ago, sounds plausible to me.

 

[scaesare]

That, combined with a lighter car and possibly new battery chemistry, could give us these numbers.

I'll point out that battery chemistry doesn't directly play in to the power/mileage efficiency of the car. The drivetrain doesn't know if it's being supplied by new Li-ion cells, old Li-ion cells, or a bunch of alkaline flashlight batteries. It simply is going to consume X wH/mi regardless.

 

[KarenRei]

Concerning the efficiency of different models, I made this from Tesla's official data. The effect of both weight and drive mode is pretty clear:

Temperature is 68°F / 20°C, windows up, AC/heating off, lights off, 19" wheels

 

[SageBrush]

I've changed my mind, and now think the 237 Wh/mile is the wall consumption for the combined EPA cycle
We don't know if it relates to the base model or the bigger battery model

If it is the base model and usable battery is 52 kWh then range is 219.4 miles and combined MPGe is 140

 

[dhanson865]

Concerning the efficiency of different models, I made this from Tesla's official data. The effect of both weight and drive mode is pretty clear:



Ed: Dang, forgot to label the X axis. It's mph. I also have a version for metric data.

Correction, the effect of changes between models is clear.

Tesla has changed

* Motors
* wheels (19" stock vs 19 aero vs 21 various)
* tires (various brands, diameters, and widths)
* battery packs
* suspension components
* various standard/optional components that add weight

to say that weight is the only thing that changed or imply that only single vs dual motor matters is rolling a ton of changes up into one sentence and misrepresenting the relationship between weight and efficiency. When Elon says there are about 20 engineering changes per week on the Model S he isn't talking about just weight.

 

[mrongey]

I'll point out that battery chemistry doesn't directly play in to the power/mileage efficiency of the car. The drivetrain doesn't know if it's being supplied by new Li-ion cells, old Li-ion cells, or a bunch of alkaline flashlight batteries. It simply is going to consume X wH/mi regardless.

True, I guess that would have no impact on the number we're discussing here, but if the batteries charge more efficiently it will improve the net efficiency from wall to road.

Another factor that technically shouldn't be included in this number but would increase efficiency is if they were able to reduce vampire drain.

If Tesla's using this number to calculate energy cost savings for marketing they might be factoring in things like this, even though technically it wouldn't be correct.

 

[GeekGirls]

That would make it more efficient than than the smaller aluminium and carbon fibre i3 - great if true though.

We have a leased i3 as a stopgap alongside our Model S, and our lifetime average is a hair over 4.2mi/kWh. That puts it almost exactly in line with the Model 3 number in play here, depending on whether or not charging inefficiencies are accounted for. It would indeed be a solid offering with great range implications if this proves to be the case.

Tomorrow evening we may not know the whole story, but we'll certainly know more! Looking forward to it.

 

[AWDtsla]

I'll point out that battery chemistry doesn't directly play in to the power/mileage efficiency of the car. The drivetrain doesn't know if it's being supplied by new Li-ion cells, old Li-ion cells, or a bunch of alkaline flashlight batteries. It simply is going to consume X wH/mi regardless.

No it does, directly. Lower IR means less internal losses to heat. Where do you think voltage drop at the pack level comes from? Not that I'm claiming the cells in the Model 3 will be that much better.

 

[Swampgator]

Also chemistry changes can increase operating voltage. If this goes up, weight goes down for a given kwH

 

[jsmay311]

The most efficient EV on the road by a significant margin per EPA ratings is the Hyundia Ioniq EV with an EPA-combined rating of 250 Wh/mile. It has a curbweight of only 3,164 lbs.
2017 Hyundai Ioniq Electric

I have a hard time imagining the significantly-heavier* (*assumed) Model 3 beating that. If it does, I will be very impressed.

But, more likely it seems that if 237 Wh/mile is a number of any real significance, it would be the battery-to-wheels energy consumption.

Here's to hoping I'm proven wrong!

 

[scaesare]

No it does, directly. Lower IR means less internal losses to heat. Where do you think voltage drop at the pack level comes from? Not that I'm claiming the cells in the Model 3 will be that much better.

IR is power lost at the cell level. That effectively diminishes what energy the cell can deliver. It does not change the power the car needs to move a mile.

 

[scaesare]

Also chemistry changes can increase operating voltage. If this goes up, weight goes down for a given kwH

He listed weight as a separate factor. Notice he said "a lighter car and possibly new battery chemistry"

 

[AWDtsla]

IR is power lost at the cell level. That effectively diminishes what energy the cell can deliver. It does not change the power the car needs to move a mile.

Yes it absolutely does. You need more of the energy stored chemically in the cell to propel the car forward. This is what the car does when it moves. Converts chemical energy to forward motion. It does not matter where in that process power was utilized, including heating the battery from resistive losses or chemically degrading the cell.

 

[SageBrush]

Correction, the effect of changes between models is clear.

Tesla has changed

* Motors
* wheels (19" stock vs 19 aero vs 21 various)
* tires (various brands, diameters, and widths)
* battery packs
* suspension components
* various standard/optional components that add weight

to say that weight is the only thing that changed or imply that only single vs dual motor matters is rolling a ton of changes up into one sentence and misrepresenting the relationship between weight and efficiency. When Elon says there are about 20 engineering changes per week on the Model S he isn't talking about just weight.

Yep

It's also easy enough to estimate since mass only plays into rolling resistance. Starting from tyre RR of 9 kg/1000 Kg mass and car mass of 1800 kg, we get 159 N. A 10% change in mass either way is good for 16 N or about 464 watts at 65 mph (105 kph).

Under 5 Wh/km, which is peanuts.

The most efficient EV on the road by a significant margin per EPA ratings is the Hyundia Ioniq EV with an EPA-combined rating of 250 Wh/mile. It has a curbweight of only 3,164 lbs.
2017 Hyundai Ioniq Electric

I have a hard time imagining the significantly-heavier* (*assumed) Model 3 beating that. If it does, I will be very impressed.

But, more likely it seems that if 237 Wh/mile is a number of any real significance, it would be the battery-to-wheels energy consumption.

Here's to hoping I'm proven wrong!

The Ioniq Cd is 0.24