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My P85D's efficiency is still improving with firmware updates

Andyw2100

Well-Known Member
Oct 22, 2014
6,542
2,443
Ithaca, NY
It's no secret that I have been pretty critical of several things Tesla has done recently. So it's only fair that I start a thread to highlight something pretty positive I think I've discovered as well.

I am fairly certain that Tesla is still tweaking and improving the P85D's efficiency (and perhaps other D's efficiency as well), either with improvements to the torque sleep algorithms or through other means. I will provide data to support this, along with a fairly thorough explanation of the data.

For quite some time, I have been recording every trip my wife makes in the Model S to and from work, as well as every trip I make in the Model S along a very similar route. I record range miles used, total energy used, and average energy used, as well as estimated temperature and estimated wind speed, other weather conditions, etc.

Her trip to work, northbound, is approximately 53.5 miles long, and her trip home, southbound is approximately 53 miles long. There is a drop in elevation of 754 feet northbound, and an increase in elevation of 754 feet southbound. The elevation changes do not take into account our long, fairly steep driveway and the parking garage she parks in at work.

My trip northbound is approximately 58.4 miles long, and my trip southbound is approximately 58 miles long. There is a drop in elevation of 630 feet northbound, and an increase in elevation of 630 feet southbound.

The two trips are identical for 90-95% of the distance traveled. Roughly half the time is spent on an interstate highway, with a speed limit of 65 MPH, and the other half of the trip is spent on rural roads with speed limits varying from 25 MPH to 50 MPH, with some traffic lights through towns, etc. Her trip usually takes her between 60 and 65 minutes. My trip usually takes me between 66 and 71 minutes.

My wife sets her TACC speed to 68 and I set mine to 70 on the highway. Neither of us use it off the highway. I probably drive somewhat more aggressively than she does, but not significantly so. I do weigh quite a bit more than she does, and am also usually travelling with our labrador retriever and her crate, my tennis bag, etc. I actually attempt to record the weight in the cabin, and the difference is generally 250 pounds or so. I set the temperature to max cooling (62 degrees) and she sets the temperature to 66 degrees.

Below are each of our average Wh/mi for our northbound and southbound legs on versions 6.2.2.4.236 and version 6.2.2.4.250 of the firmware. I believe there are enough total legs recorded and the weather conditions were similar enough that the efficiency improvement shown is significant, and due to a change made in the firmware. Our tires were just over a month old at the point we received .236, meaning they would have had over 1500 miles on them, so I don't think the improvement in efficiency could be attributed to decreased rolling resistance from tread wear. In fact, I did make a change that should work in the direction opposite the efficiency improvement, in that part way into .236 I decreased the tire pressure from 50 psi to 45 psi, based on Tesla having again changed the recommended tire pressure for the P85D. (I was a little late in making the adjustment back.) If anything, this would bias the efficiency a bit towards being better in .236.

I'm happy to try to answer any questions.

I know there will be people who say this isn't enough data to form any conclusions, and that the improved efficiency could be due to weather, different driving styles, etc. To that I say you could certainly be correct. I'm trying to supply the data as objectively as possible, so I have broken the data down by driver and leg. I don't imagine our individual driving styles have changed over the time period in question. I think there are enough legs to account for the slight changes in weather (temperature, wind, etc.) so that any weather impact would come out in the wash, so to speak.

Here's the data:


.236 (June and July)Legs.250 (July and August)Legs
Kim- North260112436
Kim- South300112956





Andy- North27052632
Andy- South32653152










Kim- All2802226912
Andy- All298102894





Overall2863227416
 

Andyw2100

Well-Known Member
Oct 22, 2014
6,542
2,443
Ithaca, NY
I just want to say that I am impressed with your Wh/mi numbers. Range mode on or off?

That's definitely with range mode on, to take full advantage of torque sleep. (Insane mode on too, not that that has any effect.) I also have 19" Cyclone wheels.

We turn off range mode when we get where we are going and plug in. My wife does not pre-cool the car, but I try to, especially since I like it cooler, and am always leaving from a place where it is plugged in, so range mode needs to be off to take full advantage of the ability to really cool the car before I start the trip. But I always turn range mode back on before leaving.

Note to Tesla if anyone is reading--it would be great to not have to do this, and have shore-powered heating and cooling of the cabin and the pack override range mode.
 

darthy001

Love my car, hope Tesla can get as great!
Oct 29, 2012
726
58
Bærum, Norway
Good news if this is true:) I' ve wondered about the same in a couple of specific driving conditions lately, but nothing conclusive as I've not needed the full range and thus has driven as I would have driven an ICE;)

Seems to be some specific speeds that is in an optimal range.

edit: this is with range-mode OFF
 

Ingineer

Electrical Engineer
Aug 8, 2012
1,507
3,712
They definitely are updating the Drive inverter firmware often, almost every update. Last night's update (2.5.36) updated the Drive Inverter, (both front and rear) but not the Autopilot. They also hit the Charger(s) and the BMS.

The update before this (2.5.21) also updated the inverters, charger(s), etc, but not autopilot.
 
They definitely are updating the Drive inverter firmware often, almost every update. Last night's update (2.5.36) updated the Drive Inverter, (both front and rear) but not the Autopilot. They also hit the Charger(s) and the BMS.

The update before this (2.5.21) also updated the inverters, charger(s), etc, but not autopilot.

I'm curious how you can figure this out?
 

sorka

Well-Known Member
Feb 28, 2015
8,608
6,458
Merced, CA
Great way to intrigue people. And good job on reverse engineering whatever it is that you reverse engineered!

He's in the Bay Area. Tesla employees thousands of people there. All of us who work there know multiple people who work at Tesla. He doesn't want to get someone who told him something in private in trouble. There's also a good chance that whatever he was told by some Tesla employee is simply wrong as well.
 

sorka

Well-Known Member
Feb 28, 2015
8,608
6,458
Merced, CA
I too have noticed improvements but wasn't sure if it was due to software or my driving. I was starting to suspect the former because my average speed has been increasing as I've become less concerned with efficiency yet the efficiency has improved anyways.
 

vgrinshpun

Well-Known Member
Supporting Member
Apr 5, 2013
5,895
22,944
PA
@Andyw2100, another thing (aside from improvement in the efficiency of the drivetrain) that can easily improve energy consumption by 15 to 20 Wh per mile is combination of higher temperature and higher humidity in July/August vs. June/July.

Both increase in the temperature (say from mid 70-ies to upper 80-ies) and the humidity (say from the dew point in the mid 50-ies to mid 60-ies) result in the less dense air, noticeably affecting the drag. I am not saying that this is definetely something that indeed happend, but it is quite likely. Usually people are not aware that temperature and humidity in this range can materially affect the energy consumption, myself included, until I dug a little to explain different energy consumption that I've observed in my car
 
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arnolddeleon

Member
Supporting Member
Jul 21, 2012
948
1,020
SF Bay Area
He's in the Bay Area. Tesla employees thousands of people there. All of us who work there know multiple people who work at Tesla. He doesn't want to get someone who told him something in private in trouble. There's also a good chance that whatever he was told by some Tesla employee is simply wrong as well.

I wouldn't bet against Ingineer.

FWIW I've seen him demonstrate some pretty crazy cool stuff with his LEAF and self-built plug-in Prius over the years. Things that clearly demonstrated that he has ability to get information and act on it.

arnold
 

Matteo

Member
Jul 6, 2015
174
34
EU
I think there are enough legs to account for the slight changes in weather (temperature, wind, etc.) so that any weather impact would come out in the wash, so to speak.

I don't understand that part. Obviously you don't mean temperature is the same in June, July and August.

The table shows that, in different months of the year your range is different. Each time you add two months to the table, your range numbers will be different until you go around a circle and complete a full year. That should be obvious. Even if you drove an S85 or P85 you would see these monthly range differences.
 
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Andyw2100

Well-Known Member
Oct 22, 2014
6,542
2,443
Ithaca, NY
@Andyw2100, another thing (aside from improvement in the efficiency of the drivetrain) that can easily improve energy consumption by 15 to 20 Wh per mile is combination of higher temperature and higher humidity in July/August vs. June/July.

Both increase in the temperature (say from mid 70-ies to upper 80-ies) and the humidity (say from the dew point in the mid 50-ies to mid 60-ies) result in the less dense air, noticeably affecting the drag. I am not saying that this is definetely something that indeed happend, but it is quite likely. Usually people are not aware that temperature and humidity in this range can materially affect the energy consumption, myself included, until I dug a little to explain different energy consumption that I've observed in my car

Thanks for the input.

I did realize that the temperature and humidity could be factors. I actually have the average temperatures for the different segments (see below), but realized that the average is somewhat meaningless. For example, on a cold morning of, say, 52 degrees, the Model S would actually be heating the car to 66 for my wife. On the more common hot days, the Model S was having to cool the cabin. I have not tried to track differential from what the HVAC was set to.

I figured that air conditioning factor evened out a lot, since on any day warmer than the 62 or 66 we were cooling the cabin to, the HVAC would have to work harder, which would at least somewhat offset any efficiency gain due to the warmer temperatures. Between those things working in opposite directions, and the relatively large number of samples, I'd like to think there isn't much variance due to the temperature, but I could definitely be wrong about that.

The average temperature for Kim's trips was 66 F on .236 and 72 F on .250. For my trips the average temperatures were 74 F on .236 and 77 F on .250.
 

AWDtsla

Active Member
Mar 3, 2013
4,282
4,255
NE
@Andyw2100, another thing (aside from improvement in the efficiency of the drivetrain) that can easily improve energy consumption by 15 to 20 Wh per mile is combination of higher temperature and higher humidity in July/August vs. June/July.

Both increase in the temperature (say from mid 70-ies to upper 80-ies) and the humidity (say from the dew point in the mid 50-ies to mid 60-ies) result in the less dense air, noticeably affecting the drag. I am not saying that this is definetely something that indeed happend, but it is quite likely. Usually people are not aware that temperature and humidity in this range can materially affect the energy consumption, myself included, until I dug a little to explain different energy consumption that I've observed in my car


Strangely, you did not include barometric pressure, which can vary wildly over the course of the day. Looking at min/max in my area, it's as much as 5.17%, which correlates to air density directly. SAE also excludes humidity from STP/NTP. Somehow this seems to work for rating everyday things, include microprocessor controlled forced induction control, which needs realtime measurement of temperature and pressure. That also means whatever the effect of humidity is, it requires no active compensation.
 

Andyw2100

Well-Known Member
Oct 22, 2014
6,542
2,443
Ithaca, NY
Strangely, you did not include barometric pressure, which can vary wildly over the course of the day. Looking at min/max in my area, it's as much as 5.17%, which correlates to air density directly. SAE also excludes humidity from STP/NTP. Somehow this seems to work for rating everyday things, include microprocessor controlled forced induction control, which needs realtime measurement of temperature and pressure. That also means whatever the effect of humidity is, it requires no active compensation.

I have not been recording barometric pressure.

I would hope that for the most part, like the other weather conditions, any fluctuations due to barometric pressure would be offset by the number of legs I recorded. I could be wrong about that.



More likely that your tires are getting broken in and range is increasing steadily due to that.

I really don't think that's it, but those of you with more experience may know better.

As I said, the tires had about 1500 miles on them when I started recording the trips discussed in this thread. For all intents and purposes, the mileage put on the car is only these trips. We do drive it at other times, but not any significant amount. So, that being the case, with 1500 miles already on the tires, would you expect to see Wh/Mi improvement of the magnitude shown, based on the additional mileage being shown? (Most legs average 53.25 miles; some average 58.2 miles.) Personally I wouldn't think so, based on the JB Straubel blog post that talked about a 1000 mile break-in period, but again, I don't have first-hand experience with this.
 

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