# Forums

## Miles per dollar: mine is 206--what's yours?

I’ve had my Model S for almost two weeks now. During that time, I’ve driven 396 miles, using a total of 128 kWh for an average energy usage of about 324 Wh/mi, which, I gather from perusing these forums, represents average energy usage. I thought I would use these preliminary figures to do some back of the envelope calculations as to how efficient the Model S is in terms of energy usage as well as its cost of ownership.

My garage circuit has a dedicated account with a time of use (TOU) plan allowing me to program the car to be charged during “super off peak hours” in which my energy cost is 1.3063 cents/kWh. I understand from previous posts that there is energy loss between the wall circuit and the car, so I have used a 15% multiplier to calculate my actual energy usage based upon previous suggestions.
Thus, in order to drive 396 miles, I’ve spent \$1.92 on energy (= 128 kWh * 0.013063 \$/kWh * 1.15).
Another way to think of this, rather than the miles per gallon (MPG) we’re used to thinking of when we discuss fuel efficiency in regular cars, is that I’m getting 206 miles per dollar ( = 396 mi/\$1.92). By comparison, my Prius (which I gave to my daughter when I bought the Model S), gets 50 mpg, and, at \$3.50/gallon, I’m getting an actual economy of 14.2 MP\$.

Obviously, depending upon where you live, and what kind of energy plan you have, this will vary greatly. It also matters, of course, HOW your energy is generated: coal, nuclear, natural gas, hydroelectric, wind, solar, etc.

I typically drive about 12,000 miles/year, so if I’m getting 206 MP\$, my yearly energy usage is just over 58 dollars.

Let’s assume I keep the car three years and drive 36000 miles. My energy cost for the three years will be roughly \$175. My real cost of owning the car, then, will largely be determined by depreciation. My sticker price prior to taxes was about \$76K. I spent another \$2K to rewire the garage. After sales tax (\$5K in Georgia), and tax rebates (\$7,500 fed and \$5000 state), my “cost” to buy the Tesla was \$67,500. Elon guarantees resale value of 50% at three years, plus a nominal amount of resale value for options. Thus my depreciation for three years of ownership should be about \$28K. So the real expense of owning a Tesla, in my situation, is not the fuel but rather the depreciation, which, at 12K driving miles per year, works out to about 78 cents per mile of driving. These back of the envelope calculations, of course, ignore other expenses such as insurance, maintenance (minimal with the Tesla), etc.

All of this is well and good, though, since most of us bought the Model S not for fuel economy but because we’re early adopters, can afford it, and tend to be fascinated by new technology. But for this technology to gain a foothold in the marketplace with a significant share, it will need to be cost effective without tax breaks. I would be curious to hear what the operating expenses are for other Model S owners in other parts of the country.

Bighorn | 08. Oktober 2013

I can already tell you that you've won that competition! Hope you're showing it to your colleagues--the one pedal driving is just like driving a phaco machine:)

Alex K | 08. Oktober 2013

I'm in Tucson, AZ. My lifetime average Wh/mi is 292 Wh/mi (about 15,500mi). Electricity is on TOU (and rates went up) and is 7.29¢/kWh (averaged over summer/winter). So 1/(0.292*0.0729) ≈ 47mi/\$ not taking charging efficiencies into account. I'm also now generating all my power from solar, so who knows how much the actual cost really is?

robert | 08. Oktober 2013

Well, since I generate all electricity with my own solar cells, the cost for that part is nil.

You're right, the cost will be depreciation and, since my car in Sweden with all applicable taxes was some 150'000 \$, that's going to be expensive.

But it seems to be worth it.

Robert

cerjor | 08. Oktober 2013

I used to have a Pleasure Way RV that got 15 mpg. Drove it for 10 years and 110,000 miles. I did all the calculations and found that depreciation was the biggest single cost, exceeding fuel.

Thomas N. | 08. Oktober 2013

I push the hell out of my car. I have no idea what the cost is per mile driven. If I cared I'd purchase a Prius instead of my P85.

tes-s | 08. Oktober 2013

I don't measure it, but I guess about 1000 miles per dollar of electricity cost. Using SC and a couple of public chargers that are convenient. Got a charge while at the movies tonight.

I figure the actual cost of my ride is about 75 cents per mile. Good for about 200,000 miles and a total cost of around \$150,000 including depreciation, electricity, insurance, maintenance, etc.

Electricity is not a big factor.

I figure my Prius is about half that.

negarholger | 08. Oktober 2013

In 6 years I will have no cost per miles - by then my solar has payed off. At least 20k miles a year for zero fuel cost. Sweet.

MNGreene | 08. Oktober 2013

Note to self: Don't buy used P85 from Thomas N, LOL.

jbunn | 08. Oktober 2013

35.7 miles to the dollar, 6 month average

Well right now I get 2.2 miles / USD :) But the Evo X slurps like a maniac. With the MS assuming 300 Wh/mile and a power cost of 3c/kWh I'd get around 110 miles / usd. Only about 50x difference ;)

Navi | 09. Oktober 2013

LOL you guys have cheap power, here in The Netherlands we pay around 23 eurocents per kWh

gasnomo | 09. Oktober 2013

I can pretty much guarantee your math is off by a decimal place. There's no way you pay 1.3 cents per kWh, 13 cents sure, as such, your math is off by a factor of 10. You've actually spent \$19.2 for those 396 miles, and thus your miles/dollar is 20ish...which is till pretty good, and inline with expectations.

gasnomo | 09. Oktober 2013

@AlexK,
your figure looks like its the service or transmission/delivery charge, both should be taken into account. while that may be your total per kWh cost, its well below the national average. Who is your provider?

Mathew98 | 09. Oktober 2013

@gasnomo - Are you in NYC with the same license plates?

It would be true for NYC electric rate. The OP stated he has a dedicated TOU meter with super off peak rate. His regular rate is likely to be much higher during peak hours usage.

Windsurfer | 09. Oktober 2013

@gasnomo: I thought my math was off too; the numbers looked too good to be true. But in fact, the state of Georgia has a very generous PEV (plug in electric vehicle) time of use plan. Here's a copy of their billing rates from their website--you can see it for yourself at http://georgiapower.com/pricing/files/rates-and-schedules/2.30_tou-pev-3... :

MONTHLY RATE:
Basic Service Charge.....................................................................................................................\$9.00
Energy Charges:
On-Peak kWh…………………………………………………..……………….……….....20.3217¢ per kWh
Off-Peak kWh………………………………………………………….………………….....6.1132¢ per kWh
Super Off-Peak kWh……………………………………………………….……………….1.3063¢ per kWh

cmaso | 09. Oktober 2013

hmmm, is this what you are looking for?

In VA... 60 kW

295 W/mi * 1.15 = 340 adjusted W/mi

340 W/mi / 1000 W = .34 kW/mi

.34 kW/mi * 0.10 \$/kW = 0.034 \$/mi

kback | 09. Oktober 2013

@Windsurfer - usually there's a generation / energy charge and a delivery / transmission charge. Are you sure there's not a transmission charge somewhere on your bill that you're not including in the calculations?

dtesla | 09. Oktober 2013

Since I have enough solar to cover my home and car. Dominion Power pays me \$80 for the surplus power. So that's -0.5 cents per mile.

gasnomo | 09. Oktober 2013

@windsurfer. pretty amazing, NY doesn't come close, that said, you'd have to only charge your car during that super off peak time, which if you do, wow, amazing, congrats....may be worth moving to Georgia. I'm in NY and paying 11.7c/kWh and thought i was doing well. (that's all in price for me too, including transmission).

NYC Realtor | 09. Oktober 2013

Initially I charged only at Beam Chargers, at \$24 per night usually came in with half charge from driving about 130 miles. -> 5.4 MP\$

Then for two months I charged at work, for "free", so infinite MP\$

Since a few weeks now I am able to charge nightly at my home garage for a fixed rate of \$50/month. I drive about 800 miles/month so now I am at 16 MP\$

Alex K | 09. Oktober 2013

@gasnomo | OCTOBER 9, 2013: @AlexK, your figure looks like its the service or transmission/delivery charge, both should be taken into account. while that may be your total per kWh cost, its well below the national average. Who is your provider?

Thats the all inclusive price which includes Delivery & Power Supply charges. There is an additional 5% credit given to off-peak rates if you have a registered EV. The provider is Tucson Electric Power. For the last 20 years I was on a grandfathered off-peak TOU rate of about 5.5¢, but that was drone away with.

gasnomo | 09. Oktober 2013

@Alex, incredible

@Matthew98 - i be the same NY plate GASNOMO...uh oh, what did i do?

hikerockies | 10. Oktober 2013

@Windsurfer - Have you taken vampire loss into account? My average is about 850 miles/month. With that many miles, I am seeing about 25% of electricity usage going towards vampire loss (8-9 miles/day, FW ver 4.5). According to car computer, I have used 996 kWh over almost 3675 miles but my egauge monitor that looks at the actual consumption at the outlet says 1460 kWh which takes charging inefficiency, vampire loss and very small use by UMC (which I leave plugged into NEMA 14-50 outlet the whole time) into account.

As an experiment, I charged my car to 70% which completed around 10:30 in the night. Next day I drove exactly 16 miles and car says I consumed 4.6 kWh for the 16 miles. In the evening, I plugged the car back in charging back up to 70%. I looked at the egauge sensor reading before starting charge and after the charge completed. According to sensor, it took 6.9 kWh to replenish the used up battery charge. That is 50% overhead for vampire loss for my 16 mile drive!

Bottom line is you need to measure actual kWh consumed at the charger, not what the car says it is consuming. 15% overhead for charging inefficiency works only if there was zero vampire loss. Depending upon how many miles you drive per day, vampire loss can become very significant.

mmknox | 10. Oktober 2013

I have a dedicated sub-meter on my EV outlet, so I am using actual electricity input (not the car's trip meters):

11,653 miles
4,093 kWh
\$0.1252 / kWh (my "all-in" Off-Peak rate

11,653 / \$512.44 = \$22.74 miles per dollar

This is since March until now. I expect it to get worse in the winter months.

evpro | 10. Oktober 2013

Even at the higher electric rates you are still getting 90 miles per gallon equivalent, with no lost time at the gas station and no exposure to carcinogenic exhaust and gas fumes.

I'd imagine that depreciation is the biggest cost of any new car, fuel and maintenance are substantially less. So like any expensive vehicle the Model S has a high cost of ownership. On the other hand it has an aluminum body, a motor that doesn't wear out and a 100K battery that can be replaced in 90 seconds with a new and probably better one. If you own it long enough that pushes the overall COO down to less than an ICE. Plus all the other benefits and your Tesla grin are included.

jandkw | 10. Oktober 2013

Mine is -\$38.60 for 7 months with about 5600 miles on my meter and I am not kidding. I had the time-of-use meter installed before my MS arrived and the result is astounding. I admit my state of NC electric cost is quite low and we took advantage of off-peak hours using laundry/dryer, washer and stuff. My 7-month of 2012 is 6586KW which costs \$801.84 or \$.122/KW. The same period this year is \$8624KW which costs \$758.64 or \$.0879/KW. I then have \$38.60 savings using my MS. What a deal. The sad thing is I took my MDX for a week vacation due to the lack of superchargers in my region which costs me about \$150 of gasoline!!!

pdx4s | 10. Oktober 2013

Windsurfer
based on Georgia PEV web site:

http://www.georgiapower.com/environment/electric-vehicles/what-rate-plan...

The Supper off peak as sated on their web site is 5 cents/KWh not 1.306 cents/KWh, which is a bit higher vs the Oregon PGE 4.22 cents/KWhr for off-peak.

The also make up for that 5c/KWh by charging 23 !! cents/KWh during On-Peak hours vs 13.266c/KWhr for PGE On-peak hours.

So I recomend you better check your first monthly bill and compare for the same month w/o an EV.

I compared mine for this Sep. vs last year (got the car on 9/6) and made aprox 1000 miles, the delta was +28\$ between EV vs no EV month.

So for me it's an av. of \$1.5/day (40 miles daily that includes climbing twice a 600ft hill) and that's with a std. 10.5c/Kwh rate.

NKYTA | 10. Oktober 2013

Miles per \$\$ for me is one less night at the clubs per month. ;-)
Okay, clearly I'm too old for clubbing, but one less "night out" with my wife covers two months worth of electrons.

At this point I've stopped obsessively keep stats on the car - plug it in at night, drive it.
:-)

Windsurfer | 10. Oktober 2013

@pdx4s: here's another link to the GA Power website which quotes the 1.3 cents/kWh figure for Super Off Peak hours:

http://georgiapower.com/pricing/files/rates-and-schedules/2.30_tou-pev-3...

Since I've had the car less than a month I haven't received a bill yet. The 1.3 cent figure may in fact be too good to be true, and it's possible that the website I quote above may be in error. I'll find out for sure when I get my bill.

wmckenzie | 10. Oktober 2013

@Windsurfer and @pdx4s:
I live in GA and also looked at the off peak rate plan from GA Power.

The premium they charge during the "day" (when you have peak household consumption usually) is fairly extreme. (0.23 v 0.13 cents) You may be giving back any advantage and then some from the off peak rate.

Depends on how/when you use most of your "other" household electricity, the majority of that coming from your HVAC in most cases.

Windsurfer | 10. Oktober 2013

@wmckenzie: Good point about the "on peak" rates. I had to establish an entirely new service to my garage to make this work, so the garage is on a separate account that is metered separately from the house. Otherwise I probably wouldn't have done the PEV plan because we have too much going in the main house during the day.

Brian H | 11. Oktober 2013

Watch out for those Supper Off Peak rates. Be careful what you chews!

@Windsurfer

If I understand correctly, I think you are actually getting about 72MP\$ based on the fact that you also have to pay the base \$9/mo service fee for your dedicated service.

12000 / (\$108 + \$58) = 72.29

Am I missing something?

Dwdnjck@ca | 11. Oktober 2013

TOU rates save me about \$200/month. My bill is lower in spite of the electricity used to charge my car. This makes my cost of driving less than zero and other calculations a waste of time.

Roamer@AZ USA | 11. Oktober 2013

Dtesla, "Since I have enough solar to cover my home and car. Dominion Power pays me \$80 for the surplus power. So that's -0.5 cents per mile."

How much did you not get paid for the energy you used in the car. By putting your surplus solar in the car you give up the opportunity to sell it back to the utility.

So your electric cost is the "opportunity cost", that you could have sold the power back for cash. You are giving up that revenue.

My utility buys back my surplus at 3.5 cents a kWh. So if I put it in my car rather than sell it back I lose the opportunity to sell at 3.5. My solar has almost amortized the install cost so I am a year from zero electric cost other than maintenance and repair someday. The opportunity cost never goes away, if you use it you can't sell it so there is a cost in the lost sale opportunity.

Bottom line is I figure energy at a penny a mile. Hard to beat that.