Tesla Model 3 Is The Most Efficient Electric Car On Highways

[Zythryn]

The ends justify the means, eh ? ;-)

I have yet to find utility in MPGe if a gasser is compared to an EV:
It says nothing about relative fuel costs;
It says nothing about relative tailpipe emissions or CO2 pollution

And if you want a cheap laugh, read how people mangle MPGe in plug-in hybrids. E.g., C&D, which has still not figured out that electricity consumption should be included in hybrid mode.

It’s not supposed to tell you about the cost or emissions.
It is there to allow comparisons between EV and ICE in a very easy and familiar way.
I have yet to hear of a better way that doesn’t require mathematical gymnastics.

As for cost and emissions, those points are listed on the Monroney sticker. Granted, the cost is based on US averages, and the emissions are woefully simplified, but that information is there.
Why some people insist that a ruler is terribly because it doesn’t measure weight I just don’t know.

 

[JulienW]

I'll guess x-sectional area too.

Heck, nothing preventing the ELR from losing efficiency in multiple areas. But CdA is likely a major cause in highway driving, and I doubt regen is very robust in city driving given the car weight and relatively small battery.

Actually regen is VEREY good and configurable. I can get up to 55 kW of regen. Also it has 2 settings and regen paddles for 3 'settings'. GM uses an obtuse nomenclature of D and L selector (like Drive and Low gear):

D = minumum regen
L = medium regen
"shift" paddles = high regen (fun and WISH Tesla would add them)

Also agree about the much higher cross section and higher CD effect. The car is a production replica of the Converj concept car so it was about form first. My main point was to note that weight was not the issue and just listed a few examples.

It does suck having such a small battery and a complex drivetrain. However it is a beauty of a car. LONG for the day I get a Tesla but I'm just not a big fan of sedans and can't afford the new Roadster. My settle for a Y but would LOVE a Model 4 (Model 3 coupe).

 

[SageBrush]

No doubt people often confuse Watts (rate) and Watt hours (amount) but would adding Joule be more or less confusing? I agree it would be more correct.

The idea would be to remove Wh from the vocabulary.

One word for a rate
A completely different word for an amount.

Even Americans do not typically mix up 'horses' and gallons, for example.

 

[SageBrush]

It is there to allow comparisons between EV and ICE in a very easy and familiar way.

OK. What are we comparing that matters to the consumer and the EPA wants to convey ?

Entropy ?

What do you think the result would be if we went up to 10 random people on the street and said "Here are the MPGe of an ICE and a BEV. The number does not tell you anything about the relative fuel costs or pollution. How useful do you find them, and in what way ?"

 

[daniel]

MPGe is good because it gives higher numbers to EVs than to stinkers. Americans see a higher number and think more is good. So MPGe will encourage people to buy EVs instead of stinkers. Your mistake is thinking that actual information has any meaning or interest to Americans.

 

[dhrivnak]

That is a happy coincidence.

The MPGe of a car does not change with the price of fuel.
Glamisdunner has reported that he pays up to 13 cents a mile ( 52 cents a kWh) to fuel his Model 3 in Escondido, CA, or about 2.5x what a Prius would cost. Does that mean the Model 3 in his area has an MPGe of ~ 20 ?

And for the reverse, I fuel up our car with PV that costs about 0.5 cents a mile. Is my MPGe about 550 ?

I suppose we could ask for a window sticker that says "MPGe: 20 -- 500. YMMV"
That should about cover it.

One can always use extreme cases. But I’d you go with national averages I think MPGe is a good approximation on average fuel cost and average emissions. And if he is paying over $.50/KWh he needs solar BAD.

 

[Saghost]

Companies like Apple and Samsung have no incentive to produce better batteries. Battery degradation is preferable when selling consumer electronics because people buy them much more often than a vehicle.

Better batteries is such a broad subject.

You're correct that cycle life doesn't appear to be a huge concern for consumer electronics - though a lot of the degradation is caused by bad operational habits - charging to 100% and then sitting on the charger overnight holding the high voltage. I think they could make better life a selling point for some customers, though.

Power density/maximum discharge rate isn't very important for them, either.

But energy density and recharge rate are at least as important for consumer electronics as they are for EVs - and again, they have bigger margins and can introduce in smaller quantities.

 

[chronopc]

Better batteries is such a broad subject.

You're correct that cycle life doesn't appear to be a huge concern for consumer electronics - though a lot of the degradation is caused by bad operational habits - charging to 100% and then sitting on the charger overnight holding the high voltage. I think they could make better life a selling point for some customers, though.

Power density/maximum discharge rate isn't very important for them, either.

But energy density and recharge rate are at least as important for consumer electronics as they are for EVs - and again, they have bigger margins and can introduce in smaller quantities.

They do have bigger margins but why would they invest in something that the consumer doesn't really care about? Most people only keep their phones for 1-2 years and while some people care about the battery technology those people are definitely in the minority. For an EV the battery technology is a much bigger deal. Tesla built a factory just to produce batteries. They own a lot of patents relating to battery technology. A company like Apple can easily do this, but they don't.

 

[Zythryn]

OK. What are we comparing that matters to the consumer and the EPA wants to convey ?

Entropy ?

What do you think the result would be if we went up to 10 random people on the street and said "Here are the MPGe of an ICE and a BEV. The number does not tell you anything about the relative fuel costs or pollution. How useful do you find them, and in what way ?"

No, not entropy, simply efficiency.

People in the United States have been used to using MPG for many decades. It has become synonymous with fuel efficiency.
If you want to compare efficiency of EVs vs ICE vehicles, MPGe is the way to do it and in a format that people will easily understand.

If you want to compare fuel prices, you look at the Monterey sticker section that estimates average annual fuel prices.
If you want emissions data you look at the (overly simplified) section.
The data is all there, just in different places than you prefer apparently?

 

[SageBrush]

No, not entropy, simply efficiency.

Ahhh ...

In the same way that an ICE that has 25% efficiency is clearly superior to a PV panel that is a puny 18% efficiency.
Got it.

----- I would love to be present during your interviews of the man on the street:
Z: So, the BEV is *3x* as efficient as your current car !
MOS: Cool. So 1/3 the cost to fuel, right ?
Z: Sorry, I do not know that.
MOS: Oh. 1/3 the pollution ?
Z: Sorry, no. Sometimes 10x more
MOS: I'm sorry too. I don't know what efficiency you are talking about and I don't care.

 

[Zythryn]

Ahhh ...

In the same way that an ICE that has 25% efficiency is clearly superior to a PV panel that is a puny 18% efficiency.
Got it.

----- I would love to be present during your interviews of the man on the street:
Z: So, the BEV is *3x* as efficient as your current car !
MOS: Cool. So 1/3 the cost to fuel, right ?
Z: Sorry, I do not know that.
MOS: Oh. 1/3 the pollution ?
Z: Sorry, no. Sometimes 10x more
MOS: What ?

Where in the world is all this coming from?
Please don’t put words in my mouth.

A. If someone is cross shopping a Camry with a PV panel, there are far bigger concerns.
B. If someone wants cost data, they should look at the cost section of the Monroney sticker. If they want more data, I’d be happy to discuss details. I have 8 years of experience fueling EVs, but that is my one case and doesn’t apply to everyone.
C. If they want more data on pollution than is in the Monroney sticker (most people sadly don’t care) I’d point the, towards the UCS site. I certainly don’t know where “sometimes 10x more” would come into the conversation.

 

[SageBrush]

I certainly don’t know where “sometimes 10x more” would come into the conversation.

Look up NOx and Sox pollution from the grid

 

[ℬête Noire]

I guess the 3AWD came out while I was away. Is it getting fewer miles per charge than the RWD? I thought the Dual-Motor Model S got slightly more range than the RWD version??? What's going on there?

The gist of the matter is that the front motor in the Model 3 is an induction motor, like the Model S, which is inherently less efficient energy transfer from battery to wheels than the Model 3's PM based rear motor. That means that combined efficiency will always be less than the rear motor alone, and (along with the extra weight) is just too much difference for the benefit of less friction loss to overcome. In the Model S the RWD motor (and the rear motor on the P) was also an older, less efficiency generation of tech than the D's induction motors. So it was mostly about the Model S D just having better tech than the RWD, and the P's efficiency likewise suffered as well because of that motor.

Interestingly, because the Model 3 Performance is using the same motors as the Model 3 non-P the Performance has indistinguishable range from the non-P unless you use that extra acceleration.

The assumed reason that Tesla went with the induction motor in the front of the Model 3 is that, beside a cheaper tech, it likely much better than the PM motor at going into coasting mode ("torque sleep") when it's not needed.

P.S. The D/P has got noticeably stronger regen, though. So on a usage cycle that was using the friction brakes a lot on the RWD the AWD would probably come a lot closer.

 

[ℬête Noire]

I find it hard to believe that a day's worth of internet connectivity takes as much energy as it requires to move a 4000lb car several miles.

It doesn't. It won't even make it a full mile, even in poor coverage areas (that tends to require even more power from the cell phone's battery).

 

[brucet999]

In open circuit permanent magnet rear motor spins freely. No problems. And there is no problem to make virtually open circuit with current motor controller.

According to a Tesla Tech I spoke to and some TMC posters on another thread, open circuit in a PM motor causes problems.

No tow mode because of permanent magnet motor?

 

[BestHand]

According to a Tesla Tech I spoke to and some TMC posters on another thread, open circuit in a PM motor causes problems.

No tow mode because of permanent magnet motor?

If it was impossible to spin motor with permanent magnets freely, Tesla M3 would not have a neutral. Here it is from the manual: "Neutral allows Model 3 to roll freely when you are not pressing the brake pedal."

 

[daniel]

The gist of the matter is that the front motor in the Model 3 is an induction motor, like the Model S, which is inherently less efficient energy transfer from battery to wheels than the Model 3's PM based rear motor. That means that combined efficiency will always be less than the rear motor alone, and (along with the extra weight) is just too much difference for the benefit of less friction loss to overcome. In the Model S the RWD motor (and the rear motor on the P) was also an older, less efficiency generation of tech than the D's induction motors. So it was mostly about the Model S D just having better tech than the RWD, and the P's efficiency likewise suffered as well because of that motor.

Interestingly, because the Model 3 Performance is using the same motors as the Model 3 non-P the Performance has indistinguishable range from the non-P unless you use that extra acceleration.

The assumed reason that Tesla went with the induction motor in the front of the Model 3 is that, beside a cheaper tech, it likely much better than the PM motor at going into coasting mode ("torque sleep") when it's not needed.

P.S. The D/P has got noticeably stronger regen, though. So on a usage cycle that was using the friction brakes a lot on the RWD the AWD would probably come a lot closer.

Thank you for this explanation. So, basically, the 3 is so much more efficient than the S that adding the extra motor does not improve overall efficiency, as it does with the less-efficient S.

I'm still envious of that 3.5-second 0-60 time. That's half a second quicker than even my Roadster!

 

[brucet999]

If it was impossible to spin motor with permanent magnets freely, Tesla M3 would not have a neutral. Here it is from the manual: "Neutral allows Model 3 to roll freely when you are not pressing the brake pedal."

Apparently you know more than a Tesla Mobile Technician. Good for you.

 

[ℬête Noire]

If it was impossible to spin motor with permanent magnets freely, Tesla M3 would not have a neutral. Here it is from the manual: "Neutral allows Model 3 to roll freely when you are not pressing the brake pedal."

It's not about being impossible, it's about how much electric potential it generates (that has a corresponding drag). This is why the "roll freely" is limited in how fast it can roll and will automatically engage brakes if you roll to far, too fast. If you were to tow it at speed causing those wheels to rotate it'd generate enough electric potential that something would have to give and damage would occur.

 

[xav-]

I keep waiting for a head to head between the Bolt and the Model 3 at 75 mph.
I know the Bolt people have given up any pretense at being a Model 3 competitor but Americans need to be educated to the difference between 'EPA range' and normative driving range on the highway.

I think the only people who are not educated to the difference between the ‘EPA Range’ and the real world range are the bureaucrats working at the EPA.