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Why a rated range instead of a rated efficiency?

gecko10x

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Jan 22, 2018
265
165
WV
Why does Tesla advertise a rated range (250/310/325, etc.) instead of the energy per mile/km (220Wh/mi, etc.)?

If they advertised efficiency, people wouldn't be fretting over displayed miles / degradation, and it would be much easier to compare across all EVs, wouldn't it?
 
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Sklith

Member
Jul 23, 2019
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GA
Tesla's cars have both a rated range and a rated efficiency. If you look at the consumption graph, you'll see a dotted line, this is the rated efficiency.
 

gecko10x

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Jan 22, 2018
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165
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I know it exists.

My point is that ICE cars are advertised with an efficiency rating (MPG), so why did Tesla change this convention? Seems like it would be better for all to go back to advertising the efficiency.
 
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gecko10x

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Jan 22, 2018
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because 99.9% of buyers would have no idea what rated efficiency means. But most everyone knows what a mile is.

Advertising 101: if people do not understand your product they will not buy it.

Just because people might not have a currently defined benchmark in their head doesn't mean they are incapable of understanding the concept.

Everyone gets what MPG means.
 

Occar

Member
Jun 20, 2019
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TN
It's meaningless in the EV context at this point in time for the average consumer. The electricity cost is so low relative to gasoline that it isn't worth it. Range is what people care about, so that's what is advertised.
 

Joshan

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Jan 8, 2019
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Chicago
Just because people might not have a currently defined benchmark in their head doesn't mean they are incapable of understanding the concept.

Everyone gets what MPG means.

yes because people know what a mile and a gallon are they use those terms every day and learn them at like 3 years old. I agree with your premise, but in reality it would likely just leave people confused and walking away. This is a country where we have to tell people coffee is hot and to remove a windshield shade before driving.
 
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rayfound

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Aug 10, 2019
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MPG makes sense for Gas vehicles because fuel is ubiquitous and fast. The only constraint on the buyer is the cost to drive, so mpg addresses that concern.

Range makes sense on EV because charging is sparse and slower, the constraint on the buyer is distance, so range addresses the main concern.
 
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SigNC

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Aug 23, 2017
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Because 220Wh/mi means almost nothing to 95% of car buyers. 300 miles per charge is easily understandable.
 

arghx7

Member
Aug 6, 2019
522
604
Michigan
the MPGe is on fueleconomy.gov , including in actual units of energy consumed per mile. Anyone can look up that up easily. It just doesn't make sense to make a big deal out of it when range and charging infrastructure are a much better sell.
 

Nocturnal

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Aug 23, 2018
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Just because people might not have a currently defined benchmark in their head doesn't mean they are incapable of understanding the concept.

Everyone gets what MPG means.
Counterpoint, people are pretty stupid. I'm not confident that much more than 50% of people understand MPG for that matter.

Efficiency is also irrelevant if you don't know your battery size. 200Wh/mi is great if you have a 100kWh battery. Not so great if your battery is 50kWh.
 

Solmors

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Jun 11, 2019
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Seattle
Counterpoint, people are pretty stupid. I'm not confident that much more than 50% of people understand MPG for that matter.

Efficiency is also irrelevant if you don't know your battery size. 200Wh/mi is great if you have a 100kWh battery. Not so great if your battery is 50kWh.
"Think about how stupid the average person is, and then realize that half of 'em are stupider than that." - George Carlin

People with <90 IQ find it difficult to calculate the cost of carpeting a room given the dimensions and price/sq ft. Seeing as roughly 1/3rd of the US population falls below 90, that's 100 million people.

I think MPGe is a horrible metric, mostly because electricity costs vary so much from place to place. The best IMO is having the estimated range and also mandating the manufacturers have to show the usable battery capacity. This way people who want to know efficiency can easily calculate it. 75kWh battery / 300 mile range = 0.25 kWh / mile = 250 Wh/mi
 
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Nocturnal

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"Think about how stupid the average person is, and then realize that half of 'em are stupider than that." - George Carlin

People with <90 IQ find it difficult to calculate the cost of carpeting a room given the dimensions and price/sq ft. Seeing as roughly 1/3rd of the US population falls below 90, that's 100 million people.

I think MPGe is a horrible metric, mostly because electricity costs vary so much from place to place. The best IMO is having the estimated range and also mandating the manufacturers have to show the usable battery capacity. This way people who want to know efficiency can easily calculate it. 75kWh battery / 300 mile range = 0.25 kWh / mile = 250 Wh/mi
Probably my favorite quote.
 

arghx7

Member
Aug 6, 2019
522
604
Michigan
"Think about how stupid the average person is, and then realize that half of 'em are stupider than that." - George Carlin

People with <90 IQ find it difficult to calculate the cost of carpeting a room given the dimensions and price/sq ft. Seeing as roughly 1/3rd of the US population falls below 90, that's 100 million people.

I think MPGe is a horrible metric, mostly because electricity costs vary so much from place to place. The best IMO is having the estimated range and also mandating the manufacturers have to show the usable battery capacity. This way people who want to know efficiency can easily calculate it. 75kWh battery / 300 mile range = 0.25 kWh / mile = 250 Wh/mi


Look on the EPA fueleconomy.gov website, the efficiency is right there. 29 kwh per 100 miles , vs 46 for the eTron. Then it converts it to MPGe and explains the conversion formula on the left.

etron_vs_model3.png
 

gecko10x

Member
Jan 22, 2018
265
165
WV
So then why do people freak out when they can't drive the full 310 miles our cars are "rated" for?

Seems pretty clear you should never actually expect to be able to drive the full rated distance, because you always want a buffer. I rarely let my ICE car get below 20% fuel; why are people trying to drive their EVs to 0%?
 

Solmors

Member
Jun 11, 2019
110
95
Seattle
Look on the EPA fueleconomy.gov website, the efficiency is right there. 29 kwh per 100 miles , vs 46 for the eTron. Then it converts it to MPGe and explains the conversion formula on the left.

View attachment 471133
Interesting, I had assumed they were basing the MPGe off of prices of gas/electricity (I think they did this at one time). But instead they are using the actual amount of energy that a gallon of gas has and calculating with that. Very cool, thanks!
 

arghx7

Member
Aug 6, 2019
522
604
Michigan
So then why do people freak out when they can't drive the full 310 miles our cars are "rated" for?

Seems pretty clear you should never actually expect to be able to drive the full rated distance, because you always want a buffer. I rarely let my ICE car get below 20% fuel; why are people trying to drive their EVs to 0%?

The whole point of the nav system in the car is to tell you when to stop at a supercharger so you don't run out of battery.
 
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novox77

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Nov 25, 2017
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the rated efficiency units that Tesla uses is so new and foreign to people. EPA is struggling with this too. In an effort to create a metric that is most relatable to the average person, they ended up using kWh/100mi instead of Wh/mi, because then the number would be 2 digits long instead of 3. This is important because mpg is typically a 2-digit number. That's the level of dumbing down we need when we're addressing the average person.

I'd also wager the average person doesn't know how kW relates to kWh, or even how W relates to kW.
 
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