Model S Equivalent Mile Per Gallon closer to 60 EMPG

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.

stimeygee | 7 aprile 2013

So is there no plan to implement a 'deep sleep' mode? This seems like a mistake.

murraypetera | 7 aprile 2013

Interesting numbers, thanks for sharing.

The eMPG for me as not as interesting as how much it cost / mile to drive.

Car 1
At 500 w/ mile in NY that is about $0.11/ mile

Coned bill/kwh $0.22/kwh so 1000w/500 w = 2
.22/2 = 0.11

Car 2
$4/ gal for 20 miles = $0.2/ miles
For 28 miles = $0.14 / mile

Tesla fixed?
350 w/ mile = 1000/360 = 2.86
.22/2.86 = 0.077/ mi

Big difference. I hope tesla fixes this vampire load soon.

f-tal | 7 aprile 2013

Where are you located? In cold weather (and I assume hot weather too), the car has a higher 'resting' power consumption to keep the batteries at an acceptable temperature. I live in the North East, and now that the weather is getting warmer, I see an improvement in my numbers. I had a meter installed to track the power going to the car via a 240V outlet. So far, (1 month, 2000 miles), I have a average of 68 mpge. (based on gas cost and electricity cost), When I do the same calculation that the EPA uses (33.7 KWH / 1 gal gas), I get 71.26 mpge, If I take out the inefficiency of the onboard chargers, I get 86.05 mpge. Since I drive 35 miles to work, the extra energy used for HVAC and battery coniditioning is amortized over more miles. Also, I reduced my electricity cost by going to a TOU rate with my utility, is that something that would work for you?

DSK | 7 aprile 2013

I'm not the expert on this, but have been reading in other threads. I have V4.2 now (and is the only version I have had so far), but there was sleep mode on V4.1 before (apparently they are working on it) and V4.3 is rolling out now, and people say that standing drain is significantly reduced. Other users have said that sleep mode is coming back in a subsequent version.

David Trushin | 7 aprile 2013

Your numbers are interesting, but probably meaningful only for you. It assumes that you spend a certain amount of time unplugged and stationary which is a characteristic of your use of the car, the rate from ConEd, and the price of gas in your location. I could do the same calculation with electricity at half the rate and gas at 5 or gas at 3.

Besides, what car has ever acheived the MPG or E-MPG rating?

Electron | 7 aprile 2013

Once again, the EPA eMPG rating is about energy use. It is not based on price per gallon, price per kwh, or any other cost, nor should it or can it be. People need to stop comparing their cost per mile with the eMPG energy expenditure per mile.

Bob Kroll | 7 aprile 2013

We lost 11 miles overnight plugged into a 14-50 amp RV park outlet in Ohio that shut down apparently shortly after we plugged in and went to sleep. In the morning, we discovered the problem, re-set the 50 amp breaker and after 15 minutes it had flipped off again. We moved the car to a different 50 amp outlet that seems to work. Here, the overnight temperature was probably in the low 50's. So why the large leakage - the batteries couldn't have gotten very cold?

stuberman | 7 aprile 2013

Can't wait for a firmware upgrade that reintroduces the feature to minimize vampire load.

Brian H | 7 aprile 2013

Some of that would still be illusory; 50° is still below operating battery temperature, and the range calculator would be thrown off till you warmed. Corrected algorithm in the works to compensate for this effect.

DTsea | 7 aprile 2013

well my car has used 816 kWh in two months to go 2422 miles (i am sitting in it!), 337 WH per miles. assuming you 3 kWh per day of loss, thats another 180 kWh for a total of about 1000. so that would be 413 kWH per mile. my electricity is 10 cents per kWh so that is 4.13 cents per mile, which at the $3.80 gas costs here is 92 mpg equivalent.

point being if you only drive 100 miles per week the vampire loss looks heavy, but with more typical 250~300 miles per week, or 12k to 15k per year, the epa numbers are right on.

my car is a 60.

DTsea | 7 aprile 2013

oh and electron the EPA rating is definitely about dollars and is based on national average electrical and gas prices to give a number relating to cost per mile of `fuel.` so you arerp right its about cost but mpge is the EPA way to calculate.

i feel bad for you murraypetera. 22 cents a kWH! OUCH! lucky for me Seattle has its own hydro plant!

Getting Amped Again | 7 aprile 2013

My numbers after 1800 miles with a 60 are almost exactly the same as DTsea ( howdy neighbor!), except I had to put premium in my ICE. Haven't bought gas for seven weeks but it's about $4 .29/gal near where I live. That makes my mpgE about 104!

lov2krz | 7 aprile 2013

I did my own calculations and come up with 76.8 move. I'm on TOU PGE E6 and pay ~$0.066/kWh. I also have 7.7kWh PV and over produce ~1200 kWh/year and expect my true up bill to be ~$100.00 next year. I'm on track for 15,000 miles in 12 months. My cost per mile is expected to be $100.00/15,0000 = $0.000666/mile. My trip meter data indicates that I use 347wm, that's based on 2400 miles driven with no reset of the meter. I loose 1/2 mile/hour vampire load based on rated range at end of charge and rated range when I enter the car after its been sitting.

Anyway, the cost per mile is still so low an ICE can't come close even at $3/gal that comes to $.0714/mile.

DTsea | 7 aprile 2013

got Amped, glad to see you got your car after so long on forums, howdy back!

Jolinar | 7 aprile 2013

+1 Electron

MPGe is about energy, not the cost (beacuse cost is different everywhere).
1 gallon of gas is 33.7kWh of energy (at least by EPA) so if you use 33.7kWh and your consumption rate is 511Wh/mile than 33.7/0.511 = 66.
So your MPGe is 66.

I heard that Tesla is working on Sleep mode so there will be much lesser vampire load while car is only sitting and not driven. Musk in Norway said that European car will be delivered with sleep so I guess it shouldn't take too long to new software version with sleep mode implemented.

Brian H | 7 aprile 2013

DTsea & Get Amped;
Do you put on more miles than you would/did on an ICE? All that endorphine-pumping driving for pleasure has to add up!

carlk | 7 aprile 2013

678 miles for 6 weeks? You are definitely not the kind of drivers who will benefit from an EV.

jdesmo | 7 aprile 2013

My calculations based on: local $0.23/KWH, 85% charging efficiency, 10mi/day average 'evaporation', 360wh/mi (car itself), $4.50/Gal, 1250mi/month yield 44 MPGe.
The EPA does not pay the bills, I do. Therefore, that is the real life number for my region.

gasnomo | 7 aprile 2013

No sure I agree with this math? I have just passed 2200 miles. Its taken about 870 KWH. To get that same mileage with my old BMW, which averaged 22mpg, That's 100 gallons of petrol. doesn't that equate to roughly 87 empg?

gasnomo | 7 aprile 2013

scratch that, my above math is completely

carlk | 7 aprile 2013

@DTsea "point being if you only drive 100 miles per week the vampire loss looks heavy, but with more typical 250~300 miles per week, or 12k to 15k per year, the epa numbers are right on."

That was my immediate reaction too. I made a similar comment before seeing your post.

I have no idea what op's real situation is but it does look to me that he/she borrowed a page from John Broder to use a not too common or even logical situation to discredit model S.

Wait till Elon Musk hears this.

gasnomo | 7 aprile 2013

I recalculated what I am getting based on the formula referenced by Electron, my MPGe after 2200 miles is 86 but that's before considering the vampire load...

jdesmo | 7 aprile 2013

Put another way: The price of premium gas here is at the moment $4.50/Gal, which is what my ICE uses.
How many miles can the MS 85 get in my region for every $4.50 I would otherwise pay the local utility?
Answer: 44 miles

mikhaila | 7 aprile 2013

Why not charge and then disconnect? Sure, Tesla recommends keeping car plugged but I bet range loss over a few night hours is not that significant.

eelton | 7 aprile 2013


With my car unplugged, I lose 12 miles per day at about 55 degrees, and 24 miles per day at an average 35 degrees. I would call that significant.

gasnomo | 7 aprile 2013


shocked at your figures...again, for my car i've driven 2200 miles, which is the equivalent of 100 gallons of $4.50 fuel for my old BMW. So at 11.5 center per KWH, I've paid $100 for electricity to drive the car that distance, or roughly 4.5 cents/mile...thus, for $4.5 the equivalent of one gallon of gas, I'd get just under 100 miles based on my usage...

EVTripPlanner | 7 aprile 2013

I have spreadsheet/tables showing electricity costs (including parasitic/parked losses) and eMPG, % savings over gas, etc at

And, yes, it is true...Tesla marketing stretches truth. Even if you drove EPA course every day, you'd never get real-world results that they get just because of static losses. These will go down a bit with software improvements, but won't go to zero.

jdesmo | 7 aprile 2013

@cfriedberg- shocking but true. As you can see, My elect. cost/kwh is double what you pay. so right there it goes from 'just under 100 miles', to just under 50 miles. So already not that far from my 44 miles figure. Your figures come to 0.395kwh/mi. We are Assuming you can actually pay just $100 to drive 2200 miles, and therefore, additional non productive hidden electrical usage such as charging efficiency and vampire drain are included in the above 0.395kwh/mi.

gasnomo | 7 aprile 2013

jdesmo, wow, you pay 22cents per KWH???? Where are you? btw, I actually took into account the vampire drain as per the OP, as my actual w/mile is 381 for those 2200 miles, so i think my calculation, for me at least, is pretty accurate...still shocked at your electricity costs, and btw, my 11.5 cents/KWH does not take into account the solar on my roof which covers about 1/4 of my electrical needs.

jdesmo | 7 aprile 2013

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.

Mel. | 7 aprile 2013

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

gasnomo | 7 aprile 2013

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.

jdcurtis | 7 aprile 2013

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.

Sudre_ | 7 aprile 2013

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.

tommy-tesla | 7 aprile 2013

$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.

shop | 7 aprile 2013

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!

jackhub | 7 aprile 2013

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.

billbaggy | 7 aprile 2013

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.

jackhub | 7 aprile 2013

BTW, if I assume the vampire is taking 10%, I'm still getting about 197 miles per equivalent gallon of gasoline. Still not bad.

gasnomo | 8 aprile 2013 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.

ChristianG | 8 aprile 2013

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.

gasnomo | 8 aprile 2013

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...

jdesmo | 8 aprile 2013

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.

village33 | 8 aprile 2013

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).

matsern76 | 8 aprile 2013

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

murraypetera | 8 aprile 2013

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.

wheatcraft | 8 aprile 2013

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.

dstiavnicky | 8 aprile 2013

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.

Mark E | 8 aprile 2013

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?