The DOJ Tesla probe has expanded to include EV driving ranges

[3sr+buyer]

The number one thing that people fail to consider is the simple fact that no one worries what the range is for an ICE car. When was the last time you complained that your ICE car only got 15 MPG rather than the advertised 25 MPG?

I don't complain, because I typically get EPA or better economy in previous ICEVs and recent EVs.

But I see complaints about not getting the EPA economy on forums for various cars including ICEVs as well as EVs. Inefficient driving habits, like trying to go 80mph on the highway, or racing up to red lights or traffic jams to slam on the brakes, result in greater consumption of fuel or electricity. So does inattentive maintenance, such as letting tire air pressure get too low in the autumn and winter.

 

[3sr+buyer]

I was thinking more along the lines of my older Ford Escape, which actually had D and L for the transmission. But since it was a CVT it did not change the gearing, but rather the algorithm to set the RPM for various road conditions.

Some EVs have different regenerative braking levels when the driver's foot is off both the brake and accelerator (this appears to be a hidden option that the aftermarket S3XY buttons can access on Teslas, and less regeneration was an option available in the UI in early Model 3 cars). Presumably, the EPA's reference to drive modes can refer to selection of regenerative braking levels.

Regarding D and L, the 2017-2021 Chevrolet Bolt had these on the selector, with L using a higher regenerative braking level.

 

[sleepydoc]

Hmmm. Good point; I didn't think of that.

I was thinking more along the lines of my older Ford Escape, which actually had D and L for the transmission. But since it was a CVT it did not change the gearing, but rather the algorithm to set the RPM for various road conditions.

A little while back Elon said something about chill mode using less energy. I can’t say for sure but it seems like it might. I generally keep my car in chill but switched it back to regular for a time and it seemed like it got worse economy. No idea if that was real or imagined on my part, though.

 

[zroger73]

A little while back Elon said something about chill mode using less energy. I can’t say for sure but it seems like it might. I generally keep my car in chill but switched it back to regular for a time and it seemed like it got worse economy. No idea if that was real or imagined on my part, though.

Elon may have repeated it, but the owner's manual says:

You can improve the efficiency of the cabin heating by reducing your selected acceleration mode. This allows the heat pump system to take more heat from the Battery to efficiently heat the cabin, instead of maintaining the Battery's ability to provide peak acceleration performance. This helps to maximize driving efficiency in colder weather. Note that when subsequently increasing the acceleration mode, the Battery requires time to warm up before the increased level of acceleration is available.

 

[David99]

Elon may have repeated it, but the owner's manual says:

You can improve the efficiency of the cabin heating by reducing your selected acceleration mode. This allows the heat pump system to take more heat from the Battery to efficiently heat the cabin, instead of maintaining the Battery's ability to provide peak acceleration performance. This helps to maximize driving efficiency in colder weather. Note that when subsequently increasing the acceleration mode, the Battery requires time to warm up before the increased level of acceleration is available.

That's very interesting. I guess I should RTFM after all

But thinking further, this means the car will use some of the battery heat and direct it to the cabin when you need heating. It wouldn't help if driving in warm weather where no heating is required

 

[mongo]

That's very interesting. I guess I should RTFM after all

But thinking further, this means the car will use some of the battery heat and direct it to the cabin when you need heating. It wouldn't help if driving in warm weather where no heating is required

Higher acceleration maneuvers are less energy efficient, so chill mode helps in that regard all year.

 

[sleepydoc]

That's very interesting. I guess I should RTFM after all

But thinking further, this means the car will use some of the battery heat and direct it to the cabin when you need heating. It wouldn't help if driving in warm weather where no heating is required

It depends what battery temperature the system tries to achieve in chill vs standard mode and the ambient temperature outside. I have no idea what the goal battery temperatures are but for argument’s sake, say the system heats the battery to 10º C in chill mode and 20º C in standard mode. If the ambient temperature is between 10 and 20º it will still potentially expend energy heating the battery. Of course the bigger the difference the more energy used. Perhaps someone knows what the battery temperature set points are and can chime in.

For me, living in MN, I can safely say a significant part of the year is spent below both of the set points so chill mode would clearly help. Personally, I never really need all the power so there’s no advantage to taking it out of chill mode and having more power on snowy days is a liability rather than an advantage anyway.

 

[David99]

It depends what battery temperature the system tries to achieve in chill vs standard mode and the ambient temperature outside. I have no idea what the goal battery temperatures are but for argument’s sake, say the system heats the battery to 10º C in chill mode and 20º C in standard mode. If the ambient temperature is between 10 and 20º it will still potentially expend energy heating the battery. Of course the bigger the difference the more energy used. Perhaps someone knows what the battery temperature set points are and can chime in.

For me, living in MN, I can safely say a significant part of the year is spent below both of the set points so chill mode would clearly help. Personally, I never really need all the power so there’s no advantage to taking it out of chill mode and having more power on snowy days is a liability rather than an advantage anyway.

I don't have data for the Model Y yet. I used to run ScanMyTesla on my old Model S for years. The car likes to keep the battery around 40 Celsius or higher depending on how you drive and ambient temperatures. But my S was an old one where the cooling system was much simpler. It would basically dump all heat from the DUs into the battery with little cooling in between. It had no way to harvest that heat for the cabin.

 

[Macb00kemdanno]

Impressive: 322 miles at 70 mph, 289 wh/mile with climate control on. My Y can’t do that for certain.

 

[David99]

Impressive: 322 miles at 70 mph, 289 wh/mile with climate control on. My Y can’t do that for certain.

Wow that is very impressive.

 

[tivoboy]

Impressive: 322 miles at 70 mph, 289 wh/mile with climate control on. My Y can’t do that for certain.

While they travelled at 70 on the highway mostly, i think they AVERAGED 62.1?

 

[sleepydoc]

Impressive: 322 miles at 70 mph, 289 wh/mile with climate control on. My Y can’t do that for certain.

well, 289 Wh/mi * 322 mi = 93 kWh. Since the MY has a 70 kWh battery there's no way it could. Now, if you increased the battery size by 35% maybe...

 

[Macb00kemdanno]

well, 289 Wh/mi * 322 mi = 93 kWh. Since the MY has a 70 kWh battery there's no way it could. Now, if you increased the battery size by 35% maybe...

For reference, 70 mph average drives for our Y (according to some digging through Tessie) are at around 328 Wh/mi. Drives with an average speed of around 63 mph are at about 295-300 Wh/mi. So it’s not too far off. I remembered wrong.

 

[alexgr]

For reference, 70 mph average drives for our Y (according to some digging through Tessie) are at around 328 Wh/mi. Drives with an average speed of around 63 mph are at about 295-300 Wh/mi. So it’s not too far off. I remembered wrong.

It depends wildly on temperature and conditions. I so as low as 210 Wh/mile for highway once.

 

[sleepydoc]

It depends wildly on temperature and conditions. I so as low as 210 Wh/mile for highway once.

Temperature and wind conditions. Wind resistance starts increasing dramatically above 40-45 MPH and a 10-15 MPH wind can make a huge difference in efficiency.

 

[sleepydoc]

To expand a bit, the force required to overcome drag is:

Drag Force = ½ * air density * Drag Coefficient * Reference Area * speed^2.

From this we see that the force is directly proportional to the drag coefficient but proportional to the square of speed. I calculated some values below but 70 MPH causes 3x the drag a 40 MPH. Even increasing from 60 to 70 uses 35% more energy.

Speed	Relative Drag
40 MPH	1
50	1.56
60	2.25
70	3.06

Now, if you are driving 60 MPH and have a 10 MPH headwind that’s the same as driving 70 MPH (=35% more energy.) Similarly, if you have a 10MPH tail wind it’s teh same as driving 50 MPH (=30% less energy.)

The astute observer will also note that air density increases with temperature. Remember that Temperature for this equation is measured in Kelvin so the difference between 20º C (68º F) and 0º C is about 7%.

Relating back to the Porsche, the Model Y has a drag coefficient of 0.23, the Macan’s is 0.25. I couldn’t find any info on the reference areas of either car other than comment stating the reference area of the Model Y is bigger than the Model 3. Their dimensions are very close so I suspect they’re about the same. The drag coefficient of the Macan is 0.02 greater or 8% greater than the Model Y so all things being equal it will use 8% more energy.

All this means that the Macan either has a much more efficient drive train or it simply has a bigger battery. (Hint - it’s the latter!)

 

[ItsNotAboutTheMoney]

To expand a bit, the force required to overcome drag is:

Drag Force = ½ * air density * Drag Coefficient * Reference Area * speed^2.

From this we see that the force is directly proportional to the drag coefficient but proportional to the square of speed. I calculated some values below but 70 MPH causes 3x the drag a 40 MPH. Even increasing from 60 to 70 uses 35% more energy.

Speed	Relative Drag
40 MPH	1
50	1.56
60	2.25
70	3.06

Now, if you are driving 60 MPH and have a 10 MPH headwind that’s the same as driving 70 MPH (=35% more energy.) Similarly, if you have a 10MPH tail wind it’s teh same as driving 50 MPH (=30% less energy.)

The astute observer will also note that air density increases with temperature. Remember that Temperature for this equation is measured in Kelvin so the difference between 20º C (68º F) and 0º C is about 7%.

Relating back to the Porsche, the Model Y has a drag coefficient of 0.23, the Macan’s is 0.25. I couldn’t find any info on the reference areas of either car other than comment stating the reference area of the Model Y is bigger than the Model 3. Their dimensions are very close so I suspect they’re about the same. The drag coefficient of the Macan is 0.02 greater or 8% greater than the Model Y so all things being equal it will use 8% more energy.

All this means that the Macan either has a much more efficient drive train or it simply has a bigger battery. (Hint - it’s the latter!)

The Macan also has the 2-gear transmission for highway cruising. It'll be inefficient for lower speeds, but it's a Porsche so it doesn't matter.

 

[drb3333]

To expand a bit, the force required to overcome drag is:

Drag Force = ½ * air density * Drag Coefficient * Reference Area * speed^2.

From this we see that the force is directly proportional to the drag coefficient but proportional to the square of speed. I calculated some values below but 70 MPH causes 3x the drag a 40 MPH. Even increasing from 60 to 70 uses 35% more energy.

Speed	Relative Drag
40 MPH	1
50	1.56
60	2.25
70	3.06

Now, if you are driving 60 MPH and have a 10 MPH headwind that’s the same as driving 70 MPH (=35% more energy.) Similarly, if you have a 10MPH tail wind it’s teh same as driving 50 MPH (=30% less energy.)

I am glad someone finally is bringing up that drag goes by the square of velocity.

It seems that a common speed among Tesla drivers is 80 mph, so I wish your table went up higher.

I very often see people say "I get nowhere near the EPA range on a simple trip on the Interstate even when cruising at a constant 80 mph". Geez.

 

[MP3Mike]

The Macan also has the 2-gear transmission for highway cruising. It'll be inefficient for lower speeds, but it's a Porsche so it doesn't matter.

I thought they dropped that in the new platform that the Macan is based on...

 

[3sr+buyer]

seems that a common speed among Tesla drivers is 80 mph, so I wish your table went up higher.

80mph would have 4 times the aero drag of 40mph, or 1.78 times the aero drag of 60mph.