AndyM
Member
When they (Fueleconomy.gov - 2012 Tesla Model S) say
Cost to Drive 25 Miles $1.14
what cost/kWh are they using? They don't seem to say.
Yep, they do, leftmost column:
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When they (Fueleconomy.gov - 2012 Tesla Model S) say
Cost to Drive 25 Miles $1.14
what cost/kWh are they using? They don't seem to say.
Yep, they do, leftmost column:
View attachment 6873
Ooops! Misunderstood, sorry.Thanks. I meant the electricy cost ($0.10/kWh for example).
The 40 kWh Model S should have about 120 mile range.?
The lighter weight of the 40 kWh S might help with city economy, but I wouldn't expect to see a significant difference in highway economy. Limited power certainly won't come into play at all in the EPA tests. Only a tiny fraction of peak power is used for the tests.It appears as if this extrapolation assumes equal weight for the 40 kwh car as the 85 kwh car. However, the 40 kwh car should be significantly lighter and may therefore receive an EPA rating significantly higher than 120 miles per charge. Of the three Model S cars its lighter weight and inability to accelerate as quickly may also lead it to receive the highest MPGe of the three. It will be very interesting to see the real numbers.
I wouldn't expect to see a significant difference in highway economy.
Comparing to an ICE car, the consumer wants the comparison of pump to wheels against wall to wheels. You pay for gas at the pump; you pay for electricity at the wall. Another way of thinking of it is that charging losses are within the car, therefore are part of the car's consumption. From a cost-to-operate standpoint, this makes sense. I've always used kWh at the wall when stating miles per kWh, as it does not require an efficiency conversion factor when going from that to cost per mile for "fuel."I don't want to get too far off topic here, but isn't that really "unfair", given that MPG is tank to wheel?
Edit: I mean in a sense when comparing to an ICE.
Meanwhile, Tesla will also offer a special tech package that boosts the range of the big 85 kWh battery by 20 miles, the maker claims.
Feds List Tesla Model S at 89 MPGe, 265-Mile Range | TheDetroitBureau.com
*doh*... well, they ALMOST had an article full or proper facts.
I would be interested to know at what rate the EPA (or contracted lab) charged the Model S at; as has been shown with the Roadster, there is an ideal charge rate that minimizes the charging losses. It probably won't move the needle much if the EPA charged at the most inefficient rate (110v), however if they did, then I can take comfort knowing some improvement in the mpg-e can be done simply by charging at 240v instead.
I don't quite understand the math here.
If it's true that it gets 265 miles with an 85 kwh pack, then that translates into 265/85 = 3.11 miles per kwh. 1 gallon of gas has 33.7 kwh of energy, so the MPGe should be 33.7 x 3.11 = 105 MPGe, no?
That's how the Fisker's EPA numbers shake out... 32 mile range on 20 kwh, 32/20 = 1.6 miles per kwh. 1 gallon of gas has 33.7, so MPGe for Fisker is 33.7 x 1.6 = 54 MPGe (close to its 'official' 52MPGe rating).
What am I missing?
Typically the manufacturer runs the numbers them selves and submits them to the EPA. The EPA lab only verifies a small fraction of the vehicles on the market each year. Not sure if the Model S was actually tested by the EPA or not. But given the scenario you can pretty much guarantee that Tesla will have chosen the most efficient charging rate to present the Model S in the best possible light.I would be interested to know at what rate the EPA (or contracted lab) charged the Model S at; as has been shown with the Roadster, there is an ideal charge rate that minimizes the charging losses. It probably won't move the needle much if the EPA charged at the most inefficient rate (110v), however if they did, then I can take comfort knowing some improvement in the mpg-e can be done simply by charging at 240v instead.
Elon actually did say during the last conference call that Tesla was going to try to get that number raised by making some tweaks to the charger or connector or something like that. I don't remember exactly what.