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How do i calculate my MPGe actuals? I drove 2000 miles and spent 85 on super charging
- Thread starter bottomsup
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I dont know, but "I drove 2000 miles and it cost me $85" seems fairly clear as it is.
Candleflame
Active Member
It depends on the average price of gas in your area. In my area, the cheap gas is about $2.30/gallon. So, $85 would buy about 37 gallons of gas (85/2.30). 2000 miles on 37 gallons would be about 54 miles per gallon (2000/37). I believe the EPA rates MPGe based on an average price per gallon of $3.17. At that rate, $85 would buy you 26.8 gallons, for an average MPGe of about 75. Supercharging will likely cost you more per KWh than charging at home will.
RayK
Active Member
I compared my driving costs between the Model 3 and my previous car, a 2000 BMW 323i, by calculating the cost per mile. For your example, 2000 miles at $85 works out to $0.0425/mi. Do the similar calculation when looking at ICE; distance driven vs. the cost in gas. You'll probably find that Model 3 cost is half as much as ICE.
Watts_Up
Well-Known Member
You could use the following Webpage: Less Than the Cost of Gas
Charging costs are approximate.
Charging cost estimate assumes Supercharger cost of $0.26 per kilowatt hour.
Gasoline cost assumes 21 MPG for Model X and Model S and 28 MPG for Model 3 at $2.85 per gallon.
Cost may vary depending on the vehicle location, configuration, battery age and condition,
driving style and operation, and environmental and climate conditions.
Charging cost estimate assumes Supercharger cost of $0.26 per kilowatt hour.
Gasoline cost assumes 21 MPG for Model X and Model S and 28 MPG for Model 3 at $2.85 per gallon.
Cost may vary depending on the vehicle location, configuration, battery age and condition,
driving style and operation, and environmental and climate conditions.
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The main takeaway is MPGe is sort of answering the question "If gasoline and electricity prices were the same thing, how far can I go?". Given that, one can only properly answer that when using local prices! So you need too calculate it. Published MPGe figures for EVs mean absolutely nothing beyond the rated efficiencies they were based on, but picked for some particular cost that likely isn't relevant to you.
The Wikipedia does a pretty good job explaining it: Miles per gallon gasoline equivalent - Wikipedia
Note that $85 isn't the whole story, since you started out with a charge at home too (which cost you some money). Roughly guessing, probably about 1800mi on Supercharging (at least, the math for that gives a more achievable Wh/mi estimate).
So if I take 1800mi that costed $85,
You can boil the formula from the Wiki article down further for your case, so that it would be
I can only guess your gas price from here assuming California. For the US, you have "expensive" gas which will make the MPGe look better than it otherwise would. Quick Google says $3.239 average for regular right now in California.
So,
MPGe will change for your car under many circumstances similar to an ICE vehicle:
In some states because gas is much cheaper, Supercharging can result in MPGe closer to 30 and even less (especially for winter driving). This directly supports the fact that long-distance travel is sometimes cheaper in a decently efficient ICE vehicle than a Tesla (assuming you don't have lifetime free Supercharging). But it usually can't be beat if you're charging at home.
The Wikipedia does a pretty good job explaining it: Miles per gallon gasoline equivalent - Wikipedia
Note that $85 isn't the whole story, since you started out with a charge at home too (which cost you some money). Roughly guessing, probably about 1800mi on Supercharging (at least, the math for that gives a more achievable Wh/mi estimate).
So if I take 1800mi that costed $85,
You can boil the formula from the Wiki article down further for your case, so that it would be
MPGe = ( Gas Price per Gallon / Total Charging Cost ) x Miles Traveled from that Charge
I can only guess your gas price from here assuming California. For the US, you have "expensive" gas which will make the MPGe look better than it otherwise would. Quick Google says $3.239 average for regular right now in California.
So,
MPGe = ( $3.239 / $85.00 ) x 1800
MPGe = 68.6
MPGe = 68.6
MPGe will change for your car under many circumstances similar to an ICE vehicle:
- Price of "fueling" ($/kWh)
- How efficiently you drive (speed, winter, etc.)
In some states because gas is much cheaper, Supercharging can result in MPGe closer to 30 and even less (especially for winter driving). This directly supports the fact that long-distance travel is sometimes cheaper in a decently efficient ICE vehicle than a Tesla (assuming you don't have lifetime free Supercharging). But it usually can't be beat if you're charging at home.
Here's an online calculator. Just plug in your car's Wh/mi and hit "convert"
Fuel economy conversions / calculator - EcoModder.com
Fuel economy conversions / calculator - EcoModder.com
But all of that is a lot less clear to anyone that OP is trying to explain to his ICE friends than "I went 2000 miles on $85". Even calculating all that out and telling someone who drives an ICE car "I went 70 MPGe" is less clear than " i spent 2000 to go $85 miles". The exercise of trying to calculate all that would be for the OP, not for the OP to tell anyone else, because no one driving an ICE car would care a bit about "MPGe".
No one asks that.. they ask "How far can you go on a charge?" "How much does it cost to go that far?" or "how much did you save doing that trip over doing it in your gas car?" All of that would be solved by "I went 2000 for $85 in this car, and I did the same trip in my previous (insert gas car here) and it cost me (insert amount here)"... that is, if the goal is actually to get ICE friends to understand the efficiency and not just figure out MPGe on the trip.
Sure, but... I mean... *looks at thread title*
EDIT: I guess there's two ways to look at it. The MPG "equivalent" could be either emissions or cost. Both are highly locally variable, with the emission data being a bit harder to get.
Yeah, there's definitely way more informal ways that this conversation actually occurs. Personally I have no friggin' clue how to answer the "How much does it cost to charge?" question (that's the specific one I usually get), because it's so much more complicated to answer (and this depends on some local context too)
- It's like $8 per charge at home! But that's not really how it works...
- Oh, you live in a stupidly inefficient house and have electric everything and are on the super expensive electricity tier as a result? Ok, then charging will now cost you about $80 (no joke, a family friend said he's at the edge of the $1/kWh tier now - adding an EV would be fully in that tier).
- Do you mean how much it costs to drive Vancouver? Because that's a heck of a lot more than $8/500km, because Supercharging.
- Do you mean how much it costs to get to Prince George? Even more! First you gotta get the CHAdeMO adapter, then you gotta use $18/hour stations, try to keep between 50-80% for maximum $/kWh due to weird CHAdeMO speed curve...
- And if I actually said all this to anyone, I'm sure they would've tuned out so I just say something like "wellllllll it depends but charging at home is much cheaper than gas for my smart car and it goes much faster and stores more but it also cost me $75k"
I've had the long-distance discussions a few times, people get really disappointed once they see that Supercharging is so close to gas prices. It's been the deciding factor when considering for a company/fleet vehicle (ones that go between job sites, not in town).
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SageBrush
REJECT Fascism
Nope
Nope
MPGe is fair useless and widely misunderstood as the above quotes show, but it is well defined. It is the miles travelled on 33.7 kWh of energy. It is useless because a kWh of electricity is quite different from a kWh of fossil fuel in terms of what it costs, how it is produced, the pollution it causes, and how much work it can perform.
OP: Do any of your friends know their MPG ? I'l guess not. Find out what they do know, and express in the same terms.I had this discussion a couple of years ago with a young girl who was given the old family truck. She was very frugal and she knew how much she spent a week for gasoline but had no idea if that was a lot or a little, or how many miles she drove.
If your friends are typical they will not know how much they drive, how much fuel they buy, or how much it costs them. If that is the case then don't waste your breath because they do not want to know.
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Sure, but... I mean... *looks at thread title*
Yeah, you are right, but I was replying to what was in the first post. The thread title and the first post are asking for two different things, at least in my opinion, since the first post says "how can I explain to my ICE friends this efficiency"... and that has nothing to do with "MPGe".
My experience is, most people know what their cars MPG is RATED... but usually have little idea how they are doing relative to that MPG, unless the car specifically has a setting to show it (like my BMWs do / did). Even then, they just know what the car says they get (if the car tells them), but the person who actually keeps track and calculates it is rare, unless they have to do it for work.
Its simple to get your actual MPG in ice cars. Trip odometer divided by gallons to fill up the tank: 300 miles on 12 gallons? 25MPG. Or am I the only oddball that did this simple math in my head after fill ups?
Hard to make a similar comparison in our EVs when the cost of electricity varies so widely. 17 cents per kwh at home versus 35 cents at supercharger during peak hours.
Hard to make a similar comparison in our EVs when the cost of electricity varies so widely. 17 cents per kwh at home versus 35 cents at supercharger during peak hours.
SageBrush
REJECT Fascism
That sort of works if the trip odometer represents one fill-up to the next. I say 'sort of' because it can be difficult to fill up the tank to the same level consistently. The auto shut-off is not particularly consistent.
Its consistent enough for MPG tracking. Even a huge discrepancy of 1/4 gallons at top off would be just 1/2 mpg off
SageBrush
REJECT Fascism
Heh
You cannot presume that the fill-up is starting from empty. Say you fill up at 1/4 for a 12 gallon tank, meaning ~ 8 gallons is added. A 1/4 gallon variation would introduce ~ 3% error. Fill like 'losing' 10 miles of range in you car due to inaccuracy ?
Well I think this goes in the basket of if I am on a train
going at the speed of light and I shine a flashlight out what happens.
Sorry I have two suppercharging events and get all my power with pannels
on my roof. This is not a hard math problem, wow, maybe more pens and paper.
going at the speed of light and I shine a flashlight out what happens.
Sorry I have two suppercharging events and get all my power with pannels
on my roof. This is not a hard math problem, wow, maybe more pens and paper.
I never fill up from Empty. Otherwise, I would be walking to the gas station with a gas can! A 0.25 gallon discrepancy on a 12 gallon fill up(Tank is 14 gallons)is a 2% margin of error. 6 out of 300 miles to me, is negligible.
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