EPA mileage not matching energy screen

[Swoosh99]

I have a MY standard range and the EPA states that I should get 244 mi @ 260wH/mi.
However, when I check my energy graph screen, it shows that the rated wH/mi line is about 220wH/mi.

Normally, a lower 220wH/mi would mean that the car is more efficient. However, in this case it's bad for me because I'm averaging 260wH/mi. I need to get my wH/mi down to a lower 220wH/mi to be able to reach 244mi rated EPA miles.

My question is, why would the rated wH/mi show a lower value than what the EPA stated?
Does your EPA wH/mi match the rated line on the rebel graph?
My battery did degrade a little to 241 mi from 244 mi. But that doesn't account for the major discrepancy.

Thanks

 

[Swoosh99]

I do not see a 260 wH/mi figure on the posted EPA sticker. As to the solid grey line you take your car battery size and divide by the EPA range. In my case my battery is 100 kWh and my range is 402, that equal 248 wH / mi which is my grey line on the graph.

Thanks for checking. How did you confirm you have a 100 kWh battery by the way? For me, my sticker shows 260 wH/mi, 244 mi range but no battery size. (I had to look at EPA test reports to find that I have a 63kWh battery)

When I search for your vehicle online, it shows that your EPA should be 288 Wh/mi.

Tesla Model S Gets Official EPA Range And Efficiency Numbers: 402 Miles

Tesla is the first manufacturer to introduce a series-produced electric car with an EPA range of more than 400 miles. Let's see the efficiency numbers.

insideevs.com

So I'm guessing the solid grey line is always lower than the EPA sticker for some reason......wonder if it is based on usable battery capacity instead of total battery capacity?

 

[ATPMSD]

You should ignore that 260 wH / Mi figure, it is an almost totally worthless and confusing calculation. You will note that the figure does not appear on the EPA sticker. The only figure that matters is the solid grey line value as that is what you need to hit to make your car’s range. ALL of the others values should only be used for comparing one EV to another.

 

[Fourdoor]

I do not see a 260 wH/mi figure on the posted EPA sticker. As to the solid grey line you take your car battery size and divide by the EPA range. In my case my battery is 100 kWh and my range is 402, that equal 248 wH / mi which is my grey line on the graph.

The EPA sticker says 26 KW/hr per 100 miles => 260 wh/mile.

Keith

 

[Swoosh99]

You should ignore that 260 wH / Mi figure, it is an almost totally worthless and confusing calculation. You will note that the figure does not appear on the EPA sticker. The only figure that matters is the solid grey line value as that is what you need to hit to make your car’s range. ALL of the others values should only be used for comparing one EV to another.

Yeah, you're right to ingore it. I did some more digging and that 260 wH/mi from EPA includes charging losses. So my actual target efficiency is 220wH/mi as shown on the energy screen by the solid grey line. That means if I drive around 220wH/mi then I should be able to attain the stated 244mi. I did not realize how high charging losses were. It makes sense that EPA includes the charging losses since that is the true energy cost.

 

[ATPMSD]

The EPA sticker says 26 KW/hr per 100 miles => 260 wh/mile.

LOL, well that was too easy! But still only useful for comparing one EV to another.

 

[ATPMSD]

That means if I drive around 220wH/mi then I should be able to attain the stated 244mi.

Correct! Assuming a full battery charge and no battery degradation of course.

 

[Fourdoor]

Correct! Assuming a full battery charge and no battery degradation of course.

And 244 miles range at 220 wh/mile gives a battery capacity of 54 kWh... much closer to the reported "usable" capacity than if you use 260 wh/mile.

Keith