# Forum

Unisciti allacomunità

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.

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

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.

Ysrman:
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?

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.

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?

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.

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?

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

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.

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.

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!

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!

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.

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

+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.

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.

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!

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

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.

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?

scratch that, my above math is completely off...lol

DTsea-

@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.

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...

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?

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.

@mikhaila--

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.

@jdesmo,

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...

I have spreadsheet/tables showing electricity costs (including parasitic/parked losses) and eMPG, % savings over gas, etc at http://EVTripPlanner.com/calcs.php

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.

@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.

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.