Are There EVs on the Market Currently Offering a Better Energy Efficiency?

[HMHM]

In my opinion, the MPGe and WH/mi are flawed. The simple reason is energy charged versus energy used. In case of gasoline, gallons of gas purchased versus gallons used may only vary by <2%. However, in case of a BEV this variation can be as much as 30%.

I purchased a 2023 MYLR7 on March 27, 2023, and have driven 1120 mi so far. I charged/purchased 350 kWH to drive 1120 miles. However, in the Tesla app under the "trips" I consumed 280 kWH. Further, it shows that my consumption per mile is 250 watt hours. Therefore, my BEV's energy usage efficiency is about 80% (100*280/350).

Now, if I calculate my overall Wh/mi based on the amount of energy purchased, my number rises to 312 Wh/mi. This means, I actually used (including the energy losses) 31.2 kWh per 100 miles. Therefore, the actual MPGe of my vehicle is 108 mi (100*33.7/31.2).

What are your thoughts?

 

[jcanoe]

The Tesla trip odometer energy usage tracks kWh consumed while driving. This does not include energy used while preconditioning or while parked when the Tesla vehicle is in standby mode while charging or when you are sitting in the driver's seat and the climate control system is running while you look at your phone, listen to music, stream videos, or play games etc.

250Wh/mile consumption for actual driving is good efficiency; this is equivalent 1/.250kWh/mile or 4 miles per kWh. 280Wh/mile overall consumption is OK. Many Tesla Model Y owners report 270 to 280 Wh/mi overall lifetime energy consumption per mile. Expect the energy consumption to be higher in winter (~15% or greater) as additional energy is used to warm the battery pack and the passenger cabin.

MPGe is a whole other can of worms as it assumes an average cost of 1 gallon of gas. I gave up trying to use MPGe.

 

[HMHM]

250Wh/mile consumption for actual driving is good efficiency; this is equivalent 1/.250kWh/mile or 4 miles per kWh. 280Wh/mile overall consumption is OK. Many Tesla Model Y owners report 270 to 280 Wh/mi overall lifetime energy consumption per mile. Expect the energy consumption to be higher in winter (~15% or greater) as additional energy is used to warm the battery pack and the passenger cabin.

Yes, thank you. My point here is to highlight the big variation between energy purchase and consumption. If I purchase a gallon of gasoline, I'm able to use nearly the whole gallon as energy. However, as I mentioned in my original post, in case of a BEV, this variation can be very high. Therefore, the watt hour consumption in the Tesla's App does truly reflect all consumption or losses due to charging, storage, battery conditioning, etc., Which can lead up to a staggering 30% loss of energy.

For the sake of transparency, the above variations should be calculated by EPA in their testing and by BEVs manufacturers in their Apps' overall energy consumption, including all energy losses.

 

[jjrandorin]

In my opinion, the MPGe and WH/mi are flawed. The simple reason is energy charged versus energy used. In case of gasoline, gallons of gas purchased versus gallons used may only vary by <2%. However, in case of a BEV this variation can be as much as 30%.

I purchased a 2023 MYLR7 on March 27, 2023, and have driven 1120 mi so far. I charged/purchased 350 kWH to drive 1120 miles. However, in the Tesla app under the "trips" I consumed 280 kWH. Further, it shows that my consumption per mile is 250 watt hours. Therefore, my BEV's energy usage efficiency is about 80% (100*280/350).

Now, if I calculate my overall Wh/mi based on the amount of energy purchased, my number rises to 312 Wh/mi. This means, I actually used (including the energy losses) 31.2 kWh per 100 miles. Therefore, the actual MPGe of my vehicle is 108 mi (100*33.7/31.2).

What are your thoughts?

No, and combustion engine vehicles dont account for time spent idling the car to warm it up in the cold in their MPH numbers either.

 

[jcanoe]

If I purchase a gallon of gasoline, I'm able to use nearly the whole gallon as energy.

The percentage of energy stored in a gallon of gas that is used to move an internal combustion vehicle is approximately 25%. The rest is lost to friction inside the engine and waste heat that leaves with the exhaust. Some of the waste heat can be used to warm the passenger cabin but most is lost out the tailpipe.

Consumption (Wh/mile or Wh/kilometer) is one way to compare the efficiency of different electric vehicles. The cost per kWh will vary by region, whether generated using solar or other means. I can estimate my cost for 1 kWh of electricity from my utility bill. This can be useful when attempting to calculate cost savings versus gas (currently this is less than 40% of the cost of using gas assuming a vehicle that gets 25 miles per gallon.) Including charging losses, etc I estimate the overall efficiency for my Tesla Model Y electric vehicle to be ~90%, perhaps even a little higher.

 

[ATPMSD]

The purpose of MPG for an ICE car is to allow you to compare one ICE car to another as you consider your purchase decision. MPGe is to allow you to compare one EV car to another as you consider your purchase decision. MPG / MPGe is really not good for comparing a ICE car to an EV.

Now if you want to calculate cost, top off your ICE car or EV, then take a weekend trip (so the car has ideal time.) When the trip is over top off again and divide the cost by miles driven. This will be the real-world cost dependent on what kind of driver you are.

 

[HMHM]

No, and combustion engine vehicles dont account for time spent idling the car to warm it up in the cold in their MPH numbers either.

Right, but we are not discussing the inefficiencies of ICEs here. ICEs will become dinosaurs and BEVs will rule. Idling is optional in both ICE or BEV, whereas charging, battery pack inefficiencies, BMS regulated commands, etc. are not optional. I'm simply talking about accounting for a BEV overall efficiency in the energy consumption calculations in the same way as gallons consumed.

 

[jjrandorin]

Right, but we are not discussing the inefficiencies of ICEs here.

You said

If I purchase a gallon of gasoline, I'm able to use nearly the whole gallon as energy.

Which is absolutely not correct, as was pointed out already, and MPG / MPGe are for measuring cars against each other, not for calculating cost to drive. Those charging losses are no different than the inefficiency of converting a gallon of gas to energy, which is much less efficient.

So, yes, you are discussing inefficiency because you are asking about MPGe numbers not containing charging losses, and stating that a gallon of gas doesnt have this as a comparison, when it does. There is no way that advertising could compute cost to charge (or cost to drive an ICE) as an advertising number because cost per gallon of gas / kWh is different everywhere.

 

[HMHM]

Despite all inefficiencies and losses, the point to take home is that a unit of gasoline is consumed by an ICE is very similar to a unit of electric energy consumed by an electric motor. I pay for a gallon of gasoline, and similarly I pay for a kWh of energy. EPA says 33.7 kWh of energy consumption is 100 MPGe. So, that 33.7 number should include all the energy losses, because I paid for those losses the same way I paid for a gallon of gasoline.

 

[ATPMSD]

So, that 33.7 number should include all the energy losses,

The EPA energy consumption numbers (MPGe - miles per gallon-equivalent) includes charging losses, so they give us glimpses of what we can expect in terms of the total energy usage. It accounts for only energy lost during the test - only.

It does not account for energy lost when the car is parked or if driven on a particularly hot or cold day. Remember the MPGe purpose is to provide comparison data, based on a standardize test, to allow consumers to compare one EV to another. It should not be used for any other purpose.

 

[HMHM]

The EPA energy consumption numbers (MPGe - miles per gallon-equivalent) includes charging losses, so they give us glimpses of what we can expect in terms of the total energy usage. It accounts for only energy lost during the test - only.

Thanks for the clarification. To be fair, it is great that the EPA testing is standardized. Do you have a resource locator for the above information? Again, I'm not talking about any optional items. All I'm talking about is energy loss occuring during charging and within the battery pack while testing. That number should be equal to energy purchased in kWh before testing. This will hopefully make the EPA testing protocol better and transparent for consumers.

 

[ATPMSD]

Thanks for the clarification. To be fair, it is great that the EPA testing is standardized. Do you have a resource locator for the above information? Again, I'm not talking about any optional items. All I'm talking about is energy loss occuring during charging and within the battery pack while testing. That number should be equal to energy purchased in kWh before testing. This will hopefully make the EPA testing protocol better and transparent for consumers.

Start here, then you can go to the EPA site for more info:

Miles per gallon gasoline equivalent - Wikipedia

en.wikipedia.org

 

[E90alex]

There is no way to account for that because it varies depending on your personal use case and the variables are not due to the vehicle itself, so it doesn’t make sense to use them for vehicle efficiency calculations.

For example charging using 240V 48 amps is going to be much more efficient than 120V 12 amps and you will “purchase” way more electricity than what goes into the battery using 120V charging.

 

[HMHM]

There is no way to account for that because it varies depending on your personal use case and the variables are not due to the vehicle itself, so it doesn’t make sense to use them for vehicle efficiency calculations.

Thanks for the resource link. Again, I'm not talking about operator's variable. In case of ICE, the EPA uses tank-to-wheel figures for calculating the rated MPG. Whereas, in case of BEV, the EPA uses onboard battery-to-wheel. All I am suggesting is to consider plug-to-wheel figures to account for all battery related inefficiencies. This is a known data point and very easy to implement. I personally believe, due to our advanced awareness of sustainability, we need a better accountability from BEV manufacturers.

 

[E90alex]

Thanks for the resource link. Again, I'm not talking about operator's variable. In case of ICE, the EPA uses tank-to-wheel figures for calculating the rated MPG. Whereas, in case of BEV, the EPA uses onboard battery-to-wheel. All I am suggesting is to consider plug-to-wheel figures to account for all battery related inefficiencies. This is a known data point and very easy to implement. I personally believe, due to our advanced awareness of sustainability, we need a better accountability from BEV manufacturers.

Your post said “energy purchased” which is what comes out from your wall and into the car. That amount varies depending on your setup.

 

[father_of_6]

If I understand correctly, what @HMHM is trying to convey is that although electric vehicles are much more efficient than ICE, there are guaranteed losses that take place just to get the energy into the vehicle (and other losses) and they're not being accounted for in the electric vehicle metrics of MPGe and WH/mi.

While I suspect we all agree, it's not something that can really be accounted for with those metrics because it varies based on the user supplied equipment and other factors.

If gasoline had to be put into an ICE the same way that wiper fluid is, some people wouldn't spill a drop, and some might spill 5% on the ground. I wouldn't expect the MPG metric to account for gas spills at the pump in it's calculations.

If gasoline evaporated from our gas tanks faster than most people could drive through it, and it's going to happen to *every* vehicle, then maybe it would make more sense to account for it... but the loss would still vary based on how quickly each driver used their gas. I just can't see how the metric could include those loses.

Now on the other hand, 30% loss is very significant... and if that's typical, then omitting that from the metrics seems very misleading. But I don't think that's typical. Is it? @HMHM - are you charging with 120v?

 

[HMHM]

Now on the other hand, 30% loss is very significant... and if that's typical, then omitting that from the metrics seems very misleading. But I don't think that's typical. Is it? @HMHM - are you charging with 120v?

Thanks for clarifying the issue further to advance the conversation. For the first three weeks, I was charging at 12A, 120V with my Mobile Connector at home. Now, I have a Tesla Wall Connector installed on a 240V, 60A circuit. I'm very happy charging at a 48A max. output of my charger.

 

[HMHM]

Your post said “energy purchased” which is what comes out from your wall and into the car. That amount varies depending on your setup.

I believe, my Tesla Wall Connector or any charger connected to my vehicle's charging port tells me, via the Tesla App, that I purchased so many kWh of energy today or during a charging session.

 

[father_of_6]

I've read many posts about the efficiency of 240v charging being much better than 120v, so perhaps the 120v were part of your initial calculations?

I've been home charging for almost 2 years and I'm not even sure if my electric bill went up. I mean I'm sure it must have, but it was likely negligible because I couldn't tell you by how much. If there's a lot of inefficiency in my charging setup, that'd be surprising to me.

 

[HMHM]

I've read many posts about the efficiency of 240v charging being much better than 120v, so perhaps the 120v were part of your initial calculations?

Not really. At 120V, 240V, or 480V, the energy purchased in kWh is not dependent on any charging equipment. In reality that is the amount of energy I'm paying for, going into my battery, but a lot less is coming out. That is why I started the thread. Furthermore, I'm supposed to accept an additional 20% reduction in the energy output of my battery in the winter time.