120MPGe is it really?…

[izzzyyd]

Is MPGe a gimmick? Is the model 3 really getting 100+ MPG?

I’m finding it hard to believe my rough estimates show it more like 30-50MPG

I guess the argument is the cost of electricity say at super chargers.

But it seems like I’m charging driving 70-80 miles and it’s time to charge again even letting SOC drop to like 6%.

When I’ve had real fuel efficient vehicles would need to fill up like once a month…

Thanks

 

[3sr+buyer]

MPGe is just miles per kWh times 33 (the equivalent energy in a gallon of gasoline). Of course, that also implies that the "fuel tank" has only about 1.6 to 2.4 gallon equivalents of energy.

Of course, your miles may vary. 70-80 miles to drain a 100% full battery to 6% implies very inefficient driving or being parked turned on (like when sentry mode is on).

 

[afadeev]

Is MPGe a gimmick?

Yes.

 

[izzzyyd]

MPGe is just miles per kWh times 33 (the equivalent energy in a gallon of gasoline). Of course, that also implies that the "fuel tank" has only about 1.6 to 2.4 gallon equivalents of energy.

Of course, your miles may vary. 70-80 miles to drain a 100% full battery to 6% implies very inefficient driving or being parked turned on (like when sentry mode is on).

Right so what is the real world equivalent of a normally driven model 3?

Being that heavy can’t see it achieving real world equivalent numbers of 100mpg+ lol

When I see these calculators 200wh/mi is like 300mpg+ like yeah ok…

Seems like the Tesla might be a true 30mpg car which isn’t very efficient at all and any fuel savings just come from the price difference of electricity vs fuel at any given point which there might be non

 

[izzzyyd]

Basically a 120mpge is the equivalent of what regular car? A 30mpg sedan, 50mpg Prius?

 

[3sr+buyer]

Right so what is the real world equivalent of a normally driven model 3?

Probably you would be surprised that many normal commute drivers get the rated economy and range or better.

 

[izzzyyd]

Probably you would be surprised that many normal commute drivers get the rated economy and range or better.

I don’t know what rated economy means in this case supposedly MPGe = MPG

Are you saying Tesla is really getting 120-150MPG?

 

[izzzyyd]

I mean if it’s true you basically just have 2 gallons of fuel capacity then yeah the car is hitting 100mpg+ and the constant refueling is felt due to the fact you can only fill up to 2 gallons and not 12-16 like other cars

 

[cwerdna]

Transportation, Air Pollution and Climate Change | US EPA

Learn how emissions reductions, advancements in fuels and fuel economy, and working with industry to find solutions to air pollution problems benefit human and environmental health, create consumer savings and are cost effective.

www3.epa.gov

It's based upon a gallon of gasoline containing about 33.7 kWh of energy. What do you add to an EV to charge it? You add energy to its battery measured in kWh.

In ICEVs, most of the energy from burning gasoline becomes waste heat and doesn't help in propelling the vehicle.

You can also look at these:

Where the Energy Goes: Gasoline Vehicles

Only about 12%–30% of the energy from the fuel you put in a conventional vehicle is used to move it down the road, depending on the drive cycle. The rest of the energy is lost to engine and driveline inefficiencies or used to power accessories.

www.fueleconomy.gov

Where the Energy Goes: Hybrids

About 21%–40% of the energy from the fuel you put in a hybrid is used to move it down the road, depending on the drive cycle. Hybrids are more efficient than comparable conventional vehicles, especially in stop-and-go driving, due to the use of regenerative braking, electric motor drive/assist...

www.fueleconomy.gov

Where the Energy Goes: Electric Cars

EVs are 60% to 73% efficient, depending upon drive cycle (77% to 100% efficient if the energy recaptured from regenerative braking is counted).

www.fueleconomy.gov

Oddly, What an electric vehicle’s MPGe rating really means, redirects to What an electric vehicle’s MPGe rating really means.

 

[RayK]

I see MPGe as a (the only?) way to compare similar vehicles to each other: BEV vs another BEV or PHEV vs another PHEV. It lets you compare which of them is potentially cheaper to run. It's not really meant to be used as a direct comparison between a BEV and an ICE, mostly because of the wildly different costs of electricity in the various parts of the country. That's not to say that gasoline prices are all that stable either.

To me, the only way to compare BEV vs ICE in electricity (MPGe) versus gas (MPG) costs is to figure out how many cents per mile each vehicle costs to operate in the environment the owner lives. Last year I created a simple spreadsheet to calculate the costs involved, using typical values/figures here in San Jose, CA. Assuming that an EV uses 300Wh/mi, electricity costs $0.38/kWh and assuming a charging efficiency of 95%, the cost comes out to $0.12/mi. An equivalent ICE that gets 40MPG with gasoline cost of $4.79/gal (remember I'm in CA and this was last summer) is the same $0.12/mi. If gas is half the price, then a vehicle can get 20MPG and still be $0.12/mi.

However, if the BEV owner has charging availability at their workplace (for free), then the cost to operate would be closer to $0.00/mi. You're not going to find that many places where companies are giving out free gas to their workers unless it's a situation where the employee is using their car for company business and they're getting reimbursed for mileage costs. But that would only cover the times when they're "on the clock". Costs to run errands to the store, take their kids to afterschool sports, go out for a Sunday drive, etc. should not be covered.

At the moment, my car (2018 LR RWD) is getting about an average of 280Wh/mi. I charge at a (subsidized) ChargePoint station where it's $0.19/kWh. That makes my cost $0.06/mi. Assuming that I was still driving my old 2000 BMW 323i (25MPG on a good day), gas would have to be $1.40/gal. Or said another way, with the cheapest regular gas currently running about $3.99 (gasbuddy.com using 95120 ZIP) near me, I'd have to have a vehicle that gets about 71MPG.

If I charged at home, PG&E costs are about double what I'm paying at the local ChargePoint station. That's why I've yet to install my Gen2 Wall Connector. Yes, it's a little bit of a hassle to go out for an hour once every couple of weeks to sit at the ChargePoint station but I'm retired, don't drive that much, and I try to combine the charging with other errands I need to run.

 

[gsmith123]

Right so what is the real world equivalent of a normally driven model 3?

It might be helpful to take a step back and consider: what question are you really wondering about?

Is it:
- how do the carbon emissions from a Model 3 compare to ICE vehicles?
- how do operating costs compare to an ICE vehicle?
- something else?

Are you saying Tesla is really getting 120-150MPG?

There's just not a single yes or no answer to this. Miles per gallon has no direct equivalent for an EV; any equivalencies people draw assume you're trying to answer a specific question.

The closest you'll get is that a Model 3 can do 3-4 miles per kilowatt-hour (which isn't terribly useful in itself, but could be useful for estimating operating costs, for instance).

any fuel savings just come from the price difference of electricity vs fuel at any given point which there might be non

That statement can't be false; definitionally the lower "fuel" costs of an EV arise from the relative prices of electricity and gas.

For the foreseeable future, residential electricity prices are likely to remain low enough to lead to substantial operating costs benefits for EVs. DC fast charging on the other hand is very expensive and comparable to gasoline costs.

 

[mpgxsvcd]

MPGe is there to illustrate just how wasteful an ICE car really is.

If you have a 15 gallon gas tank then that is the equivalent of a 500 kWh battery(15x33.4). Yet you probably can only get 300-400 miles out of that 500 kWh of stored energy.

2/3 of the energy in the gas is typically wasted in an ICE car even with the most efficient driving style.

If an ICE car goes 400 miles with 500 kWh of stored energy it is getting 1,250 wh/mi or 26 mpg. I am averaging 213 wh/mi recently and 261 wh/mi overall in my Model 3 Performance. That is the equivalent of 156 MPGe recently and 128 MPGe for the lifetime of my vehicle.

Some people wonder why eFuel or synthetic gasoline hasn’t caught on yet. At the very minimum you have to put 33.4 kWh of energy into creating 1 gallon of gas. However, in reality the number is probably closer to 300 kWh per gallon of eFuel created. Then you throw 60%+ of that energy out the window when you combust the gasoline. It is just so incredibly wasteful.

 

[Zythryn]

I’m finding it hard to believe my rough estimates show it more like 30-50MPG

If you could show us how you calculated that, we might be able to answer your question.

In short, no, MPGe is not a gimmick. MPGe is a mathematical conversion. It converts the electricity used to propel a vehicle into a miles per gallon equivalent.
MPGe has nothing to do with cost, it is purely an energy efficiency gauge.

 

[KenC]

Right so what is the real world equivalent of a normally driven model 3?

Being that heavy can’t see it achieving real world equivalent numbers of 100mpg+ lol

When I see these calculators 200wh/mi is like 300mpg+ like yeah ok…

Seems like the Tesla might be a true 30mpg car which isn’t very efficient at all and any fuel savings just come from the price difference of electricity vs fuel at any given point which there might be non

I get 4miles/kWh, and my electricity costs 20c/kWh, so around a nickel/mile. My BMW got around 20mpg, so multiply the nickel by 20, and the equivalent is like buying gas for $1/gallon for my old BMW. That's my real world equivalent, how does it relate to my old car.

 

[E90alex]

Right so what is the real world equivalent of a normally driven model 3?

Being that heavy can’t see it achieving real world equivalent numbers of 100mpg+ lol

When I see these calculators 200wh/mi is like 300mpg+ like yeah ok…

Seems like the Tesla might be a true 30mpg car which isn’t very efficient at all and any fuel savings just come from the price difference of electricity vs fuel at any given point which there might be non

How are you getting your result that it’s a “true 30mpg car”?

Yes, electricity is much more efficient than gasoline because about 2/3 of the energy in gasoline is lost as heat.

As already mentioned, MPGe is just a calculation based on the average energy content in a gallon of gasoline that the EPA has set at 33.7 kWh.

I average 245 Wh/mi in my Model 3 Long Range. That equals 4.08 mi/kWh. That would give a calculated MPGe of 137.5.

 

[gottagofast]

Based on my electricity price and the current price per gallon of gas my car is equivalent to 210 miles per gallon

It costs me $1 to charge 70 miles worth of range in my car and gas is $3 per gallon, $3 worth of electricity gives me 210 miles

 

[rpiotro]

Only 120 MPGE? What model is that? Mine is rated at 142! Still the highest rating of any BEV.

2021 Tesla Model 3 Standard Range Plus RWD (fueleconomy.gov)

 

[fhteagle]

MPG was a problematic unit even when applied to liquid fuel burners. L/100km is a much more sensible unit for quite a few reasons.

MPGe is even more nonsense, especially because the grid is dramatically different in different parts of the country. But the figure helps people to compare apples to orangutans when car shopping.

A better comparison is MPG vs mi/kWh, because that ratio x electricity price in cents = equivalent liquid fuel cost in gallons. 20 mpg / 2mi/kWh = 10 x $0.14/kWh means I would pay the equivalent of $1.40/gallon to fuel an F150 Lightning at home, for example.

Fun little factoid: an EV charged on solar power produces less gCO2e per mile than the fossil fuel industry wastes bringing the fuel to market.

 

[mpgxsvcd]

From an economic perspective $/mi is the only thing that matters. That is a great metric for comparing ICE to EVs. When Supercharging during peak hours ICE can actually match an EV in some cases for $/mi.

When charging at home or work is where EVs really shine for $/mi.

 

[David99]

Some people wonder why eFuel or synthetic gasoline hasn’t caught on yet. At the very minimum you have to put 33.4 kWh of energy into creating 1 gallon of gas. However, in reality the number is probably closer to 300 kWh per gallon of eFuel created. Then you throw 60%+ of that energy out the window when you combust the gasoline. It is just so incredibly wasteful.

That is the best way to explain why e-fuels are not a good alternative let alone an alternative. Burning something to create motion just isn't an efficient method, no matter how or what.