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Model S Equivalent Mile Per Gallon closer to 60 EMPG

I noticed that my model S was "leaking" range every day it sat unplugged so I decided to get a real idea of the effect of this on E-MPG. I also wanted to know exactly what I was paying for the car per mile so i installed a household watt hour meter like the one on the side of the house right before the wires go into the charger. I have tracked the KWH usage by the charger over the past 6 weeks or so and have come up with 351kw took the car 687 miles. This yields an efficiency of 511wh/mile. at 4.00/gallon and .14/kwh this period yielded 56mpg equivalent. which is a lot different than the 89 empg that the epa rated this car at. The car seems to us 3kwh per day just sitting there. Over the 28 day period i checked this that would account for 84 kmh of the 351. if you take that out the efficiency would have been 388wh/mile or 74empg (getting closer). and i am told that chargers are 90% efficient or so? (correct me on this if someone knows the actual on a 220v 40amp plug) So if the charger were 100% efficient and they could find a way to fix the daily leak the car would have done 350wh/mile which is a lot closer to the 325wh/mile the screen claims in the trip log over the same period.

So leaving the computers on is robbing me of 18mpg.

cfriedberg, $0.225/kwh in Long Island. Also the north shore is hilly and dense,so no solar panels around here.
I doubt TM would sell many cars around NYC/L.I area, if intelligent comparisons are made, as we do here.
In addition, with $700/year for maintenance, and high purchase cost the MS is also more expensive in this regard - specially for people who lease a new car every 3-4 years.

jdesmo, where are you making these intelligent comparisons? Is it in the hilly and dense area?

Jdesmo. I'm in Westchester country. Shocking your rates are double so close.

But notice the window sticker from your MS. Mine says 89 MPGe, and states 38kwh per 100 miles with a 265 mile certified range at full charge. But if its 38kwh/100 miles and its an 85 kwh battery that only gets you 223 miles of range. And again since I got my car the inception to date watts per mile is 381, spot on the wonder sticker figure.

Several people keep listing their "actual KWH usage" in their cost calculations. How many of you have mounted a meter on the wall that tells you what the car is really costing you as i have? What the car says the kwh usage is is irrelevant. What matters is what you are paying for to the charger. I am not slamming the model S, as there are three of them in my family already, I just thought it was interesting to note that this vampire loss is significant and the car could be about 25% better efficiency for me if it were fixed.

If my electric cost ever gets to more than 20 cent per kWh I am moving or installing solar. If trees are in the way they will get topped. Even without tax credits solar pays for itself at 20 cent a kWh.

The 1000+ miles I drove the first month I had my S cost me less than $35. My Saturn would have cost me more than $165 in gas.... that's not including losses with the Saturn because in winter I would start the car and burn the gas while it warmed up, that's included in the S costs. It also does not include the ICE losses because most of the driving is city and bad gas mileage, that is included in the S costs too.

I don't care about the MPGe. I am happy saving $130 a month.

I have noticed that currently I am driving more than I did with my Saturn because it's fun to drive again.

$0.22/kWh? That's cheap. I'm paying $0.34/kWh (the MS kicks me into Silicon Valley's PG&E Tier 4 really fast).

Even ignoring the cost of the car and the vampire loads, it costs
me the equivalent of a 4/(0.342*0.34) = 34 mpg car (342 Wh/mi is my 3,600 mi average and I'm assuming $4/g premium gas).

Alas, solar is not in my immediate future.

OT, but guys, don't be shocked at $0.22/KWH electricity rate. Here in San Diego, the utility charges a tiered rates (4 tiers) and if you have a moderately large house, you will be in the 4th tier, meaning Tesla charging will be at that rate. And that rate is ... 0.28/Kwh. The only saving grace is that SDG&E does have a Time of Use rate which will mean "only" 0.16/Kwh after midnight.

And yeah, solar electric and fuel cells ( make a lot of sense here!

I'm averaging 330wh/mile or about 3 miles per Kwh. I'm paying an off peak rate of $0.05183 per Kwh. That's $0.05183 per 3 miles or $0.0172766 per mile. If I divide that into the local cost of gasoline which is currently $3.79 per gallon, I get 219.37 miles per dollar equivalent gallon. Not bad.

I am in SoCal and am always in Tier 5 with SCE, so cost of electricity for charging my Model S would be $0.33/kwh. This is why I got solar. Completely covers charging my Tesla at around $0.09/kwh..

I have driven 6,264mi in the past 3 months of having the car with an average energy consumption of 347 Wh/mi, 2175 KWh total.

I realize that I have not actually measured the draw from the outlet, but my estimates on additional energy consumed by the car, based on the Tesla energy estimator, as well as tracking my actual additional usage through my utility, I am running pretty close to what the car is telling me. I realize that there are several KWh lost per day in just having the displays on, which increases the overall actual Wh/mi figure. So it should go down when we get a sleep mode that works.

Anyway my calculated MPGe, based on the CA formula is

MPGe = 32,600 / (consumed Wh per mi) = 32,600 / 347 = 93.94

EPA formula: MPGe = 33,705 / 347 = 97.1

I'll take that..

My driving has gotten much more subdued over time. Still like to punch it from time to time and mainly drive in the 65-75 mph range, but at steady speeds. I have seen my Wh/mi usage come down over time. When I first got the car I was always in the 400-450 range. Over the last month, I drove 2048mi at an average of 336 Wh/mi, 687.3KWh total.

BTW, if I assume the vampire is taking 10%, I'm still getting about 197 miles per equivalent gallon of gasoline. Still not bad. Completely get what you're saying. I have t installed a watt meter but I thought I included your vampire drain figure in my calculations as I noted...but I get and agree with your basic point which is the vampire drain issue needs to be fixed.

While the Vampireload defenitely has to be fixed I always wonder how you can buy such an expensive performance car and then complain about safing only $40 instead of $60... If money is the thing you're after you'd never have bought this car.

I think the point is more that this is a technology issue and an efficiency issue which could impact broader adoption vs the OP making a financial issue out of it. Even Elon has said this is going to be fixed. I don't think the OP was making a gripe about $ and cents...

I agree with you. However it is TM leadership that keeps making some absurd claims about cost of ownership all the time.

@shop,@tommy-tesla - you should humbly defer to @Mel to set you right - he sure put me in my place.

I agree Tesla should minimize the load, but you need to drive the car to save money. Less than 100mi a week is hardly driving it (I drove 1600mi this week and wish I could have taken the Tesla but will in the future). At less than 100mi per week, that's 8 mi a day. With the puff of exhaust, running it cold and bringing the engine block to temperature, the 16oz+ of gas you burn (in excess of EPA rated usage) will also knock your ICE range down the 25% you are seeing for the short runs you are talking about. Also, there are other threads on this, but I'd expect the Tesla to run 25% less efficiently if you choose to always run it with a cold battery (which probably takes 15mi to warm up unless you do proper battery/heat pre-drive warm-up).

You Americans can try to do the same figures based on our gas prices here in Norway. For me the Tesla S is a must have vehicle - and the number of reservations are now peeking straight up.
Price for the Tesla S 85kw in Norway is - 87 000 USD
A merecedes S-class 350 L costs - 200 000 USD.

Gas price in Norway - Standard unleaded petrol = 10 USD / gallon.

Electricity is now for april - 0,13 cents /kw

Normal price summer = 0,09 cents /kw

I posted the $0.22/kwh in westchester NY.
My rate is $0.085/kwh but when I add in my transmission costs and taxes...

I think a lot of people are looking at how much they pay/kwh. What you really need to do is take you total$/kwh = $/kwh

i.e. used 1120 kWh last month
ConEd $146
Supplier $95

= $241/ 1120kwh = $0.215/kwh including all taxes, etc.

We even have some solar but it is about 12 years old and does not supply more than about 10kwh on a good day.

Vampire load really needs to be addressed not just to TOC of the car but to have the ability to leave it at the airport which is currently not possible.

Everyone talks about parasitic losses, and if Tesla can improve that, so much the better. But did anyone stop to think about the equivalent parasitic losses in an ICE car? It's called SITTING IN TRAFFIC! Yes, I know there is no way to quantify this and it varies, depending on where you live, your commute, etc. But when the Model S sits in traffic, there is no engine idling, just a few watts to keep the screens lit, which is, I'm sure, negligible compared to an idling ICE car.

interesting numbers and research. At the end of the day it depends more on what you pay for gas and electricity. In Toronto Canada, we are paying much closer to $5 gallon for premium gas and only 0.08 cents for kwh electricity. So the difference is HUGE.

It never ceases to amaze me how impossible it is in the US to get a straight answer on how much things actually cost. There is always some other charge or tax creeping in.

eg. 1. The cost per kWh doesn't include transmission or taxes? How are you supposed to work out what you need to pay?

eg. 2. When you buy something in a shop there is always a tax above the printed price

eg. 3. Staying at a hotel there is always extra for tax, some 'resort charge' or other, etc etc

Here in Australia the price is the price, including taxes and generally other charges. Much simpler.

Just how do you get charged for electricity in the US? Is it always a per kWh plus transmission, or does it vary by state?

I don't know of any utility that imposes a separate transmission charge on residential users. Taxes are something else.

@Mark E, I agree with you and I live in the US. There is nothing confusing about an electric bill, every bill shows X power delivered and Y $ total cost. A monkey could read it. There is a breakdown of sub charges (in CT including production, taxes, surcharges, transmission, etc) but only the total cost per kWh matters. In CT I can choose my producer and production vs transmission is about 50/50. My total cost is $0.13/kWh. For those who care in CT it is 50/50 nuclear/nat gas (green/clean).

@DouglasR, in CT there is a production section per kWh and transmission section per kWh. This is necessary since we can pick both producer and price lock period (floating, 6mo lock, 12mo lock, etc).

Nothing complicated about either, but it does vary by state and within a state by utility.

just for the record, my 11.5 cents/kwh is total cost, that includes NYSEG and supplier costs which breaks down 5.5 cents and 6 cents respectively...same figure as when i take my total bills for the last 12 months divided by total usage...

I asked Tesla service if the total kwh used included the vampire drain and he said yes. By the total kwh used shown in the car, I am getting 90 miles per gallon equivalent at $4.00 a gallon for gas and paying 11 cents per kwh. I drive alot and believe I am saving a lot of money everyday compared to my BMW.

@village33 - I stand corrected. I used to follow this stuff pretty closely, but it looks like things have changed since then.

@lgagliardi - I'm not sure what you mean by "total kwh used," but if you are referring to the kWh figures in the trip meters, they measure consumption only when the car is moving. Just look at the total kWh used "since last charge." Charge your car, then unplug it for a few hours. You will see the Rated Miles decrease even though kWh used since last charge stays at 0.

@DouglasR - we pay a certain amount for production and another set rate for transmission. We are in a deregulated TX market. Transmission is is fixed price set by the line utility, the production cost is the one that has price competition by producer. This is for residential and commercial.

If each car does 10K in a year, and is written down to 50% in 3 yrs, that's
$100K for the S350 + (25 mpg) 400x$10=$104,000 for 3 yrs or $3.34/mi.

$43.4K + (13+9)/2=$.11/kWhx2.5x300=$82.50= $43,582.50 or $1.45/mi.

So the S350 is 2.3x as expensive.

The above assumed 400Wh/mi, for difficult and aggressive driving.

Note that comparative fuel costs are $4,000 vs $82.50.

Reading this thread reveals one thing for sure. Electric utility rates in the US vary all over the place- not just the level but the structure, too. I pay an off peak rate of 0.06089/Kwh including everything. Bottom line. At an average of 330wh/mile and $3.75/Gal of gasoline, I am getting about 187 EMPG with no vampire effect. If I assume 10% loss for the tooth fairy, I am still getting over 168 EMPG. I behaved myself this past week and got 300wh/mile. So this past week I got 185 EMPG including the tooth fairy. Still not bad.


I thought the service guy was wrong. I am getting a separate meter installed for the car under the utility company NIPSCO ev program. I will get free charging till jan of 2013. Then I will know exactly what the car is using. Regardless what it is, I really enjoy the car and not going to the gas station!

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