Excessive Wh/mi at highway speeds

[andyemm]

Hello all! I'm new to the TMC forums and Performance Model 3 (with 20 inch wheels) ownership. I've been struggling with the range of my vehicle, as the computer never seems to accurately calculate expected energy consumption during long range trips; even after over 7,000 miles on the odometer. Using the data from the Tesla Range Table at Teslike.com and self procured data from recent trips, here are my following assessments:

According to TesLike's Range Table, at an average speed of 75 mph (average interstate speed limit in Texas) with the P3D+ 20 inch wheels, I can expect to travel 252 miles. Assuming that the battery's capacity is 75kWh, I can solve that the average Wh per mile is 297. (75,000Wh / 252).

During my last 164 mile trip, the navigation calculated that I should arrive with 22% battery capacity while starting with 91%. Assuming that the computer expect to use 69% of the battery or 51.75kWh (75kW of total capacity x 0.69), I can then calculate that the computer expected to average out at 315.549 kW/mi. (51,750Wh / 164).

Okay, now for real world results with an exterior temperature of 75*F at a top speed of 75 mph: 355 Wh / mi, which in theory would have knocked me down to 14% (164 miles * 355 = 58.22 kWh, 58.22 kWh / 75kWh = 0.776 battery capacity lost, subtracted from 91%), but in reality somehow knocked me down to 10%. I am *Not* driving aggressively and was using cruise control for the entirety of my drive.​

Observing this data, I'm finding that my real world energy consumption is 1.125 times more than the computer is expecting to draw, and 1.195 time more than the data from TesLike. I quite literally cannot trust the navigation's estimated capacity upon arrival, especially on trips with a charge in-between as it is quite unpredictable. On my 250 mile trip to my family's home, If I were to leave when the navigation system says I can, the battery would surely die far before my arrival.

I am concerned because this is not the battery performance / trip planning accuracy that I've witness from other Teslas owned by friends. However, Tesla's diagnostic team is telling me that the batter is functioning as expected.

I'm really not sure what to do, if this is actually normal, or how to go about it when Tesla is telling me that everything is fine. Does anyone have insight into this? or have a similar experience yourself?

 

[Zoomit]

What were the winds like for your trips? Even what seems like "calm" winds can have a noticeable effect and it doesn't take much of a breeze to exceed the predicting consumption by 10-20%.

 

[vjason]

I get this as well. Wh per mile displayed and actual battery capacity usage aren’t matching up, and haven’t for some time. Been awhile since I had a trip long enough to check but your numbers seem familiar.

Personally I don’t worry about it so long as I don’t lose any more capacity. Been at ~291 since the infamous update(s) Last year but it seems to be holding there.

 

[Silicon Desert]

Hmmm, I am thinking that you are looking at this in too granular style. 1/8 more use than Tesla calculates is just not that much different in my opinion when possibly considering wind resistance, road conditions, extra weight, A/C, tires, and other factors. You remind me of a good friend that likes to calculate how many feet of travel he can get from his Honda with an ounce of gasoline Seriously, just trying to make a funny point and not give you a hard time. Maybe there is something I am missing in your post. If there is, then feel free to correct me. Battery calculations are just not that granular. Just enjoy that puppy

 

[joebruin77]

Have you checked out the basic factors that can effect range and energy use? For example, have you checked your tire pressure? I have found that increasing my pressure by 2-3 psi above the recommended setting helps improve energy consumption quite a bit. Do you minimize how much you use the heater, defroster, and AC? Do you drive with the windows down or up? Do you carry anything heavy in the frunk or trunk?

I noticed an improvement in my energy efficiency after getting ceramic tinting installed on all my windows. The ceramic tint significantly reduces the AC use in the summer.

Hope that helps.

 

[XLR82XS]

Have you checked out the basic factors that can effect range and energy use? For example, have you checked your tire pressure? I have found that increasing my pressure by 2-3 psi above the recommended setting helps improve energy consumption quite a bit. Do you minimize how much you use the heater, defroster, and AC? Do you drive with the windows down or up? Do you carry anything heavy in the frunk or trunk?

I noticed an improvement in my energy efficiency after getting ceramic tinting installed on all my windows. The ceramic tint significantly reduces the AC use in the summer.

This is true. I keep AT LEAST 41psi in all tires and my A/C does not run very hard with ceramic window tint. Even with our 90F+ days here recently my A/C is not working that hard and my energy consumption is less compared to no tint.

My kwh/mi also dropped a tiny bit in the last couple weeks since lowering the car.

 

[NovemberXray]

I have done many long road trips, coast to coast USA, all over the Western US, and have driven about 150k miles now in the last 4 years in Tesla Model X, 3, and now Y. A Better Route Planner is a very helpful tool for planning, but I have found that the onboard car trip planner is reliable to +/- 10%. Often times it's within only 2%, but worst case, in all weather conditions, even in winter with the heat on, and snow, I don't think I ever arrived with less than 10% LESS than what the car predicted. You can also manage this pretty easily by slowing down if needed... so as some have suggested, I encourage you to use tools like A Better Route Planner to be informed before a trip, but to worry less and change your battery display to energy, rather than miles; I am totally comfortable if my car says I will arrive with 15%, sometimes even 10% that I will make it without trouble. I only ever think about it in terms of arriving at my destination with the desired charge level, not a certain number of miles.

 

[holmgang]

Observing this data, I'm finding that my real world energy consumption is 1.125 times more than the computer is expecting to draw, and 1.195 time more than the data from TesLike. I quite literally cannot trust the navigation's estimated capacity upon arrival, especially on trips with a charge in-between as it is quite unpredictable. On my 250 mile trip to my family's home, If I were to leave when the navigation system says I can, the battery would surely die far before my arrival.

Yes the EPA rating varies widely from actual rating, more in this car than many other electrics (and combustion, for that matters).

But the trip computer is actually very, very good: the consumption is based on the mapped route (its speed and elevation) and your recent consumption.

Unless you drive completely and utterly quicker than normal, the %remaining-at-destination estimate is good at the start of a charge, and converges to better estimate as you drive. (it's like the ETA -- it's continually adjusted during the trip).

Let's say you're on a full charge and it predicts 20% at arrival. If half way through the leg you find it projects 10% at arrival, being more cautious of driving habit will restore it to 15%, 20%, giving you plenty of safe buffer.

Often I can go positive on the projection, without significantly changing how I drive. TLDR computer estimate is very neutral (i.e. not systematically biased), and car has excess capacity to deviate from that estimate without dying on the road.

 

[jmaddr]

Have you looked at the energy app?
Rather than calculate your KWhr/mile, open the energy app and watch what conditions cause your consumption to rise over the past 5/15/30 miles. If you want a longer exact number, just set one of your two trip odometers as that too gives you kwhr usage over the trip odometer miles.

One thing I don’t know is if the computer calculates your speed as the average over your past X miles or at the speed limit of the entered trip. I suspect it’s the speed limit and my experience has reinforced that..and with you at 75, that extra 5 mph does make an impact, and that’s assuming it’s 70 when you are going 75. Your calculations of an extra 12.5% to 19.5% may not be unreasonable.

 

[Ultron]

Yep, Same car as OP and after 10 months of use I only plan to go about 200 miles between charges. Anything longer and you better slow down and pay very close attention to battery. I like to drive with no constraints. If a Mustang 5.0 pulls up beside me revving engine I want to be able to teach him a lesson without having to worry about making my destination. I also find the energy graph in the car much more accurate than the battery %.

 

[andyemm]

One thing I don’t know is if the computer calculates your speed as the average over your past X miles or at the speed limit of the entered trip. I suspect it’s the speed limit and my experience has reinforced that..and with you at 75, that extra 5 mph does make an impact, and that’s assuming it’s 70 when you are going 75. Your calculations of an extra 12.5% to 19.5% may not be unreasonable.

I followed the speed limits to the tee, Texas highway speeds FTW! I was told by Tesla service that it does adjust to driving habits over time though.

Let's say you're on a full charge and it predicts 20% at arrival. If half way through the leg you find it projects 10% at arrival, being more cautious of driving habit will restore it to 15%, 20%, giving you plenty of safe buffer.

Often I can go positive on the projection, without significantly changing how I drive. TLDR computer estimate is very neutral (i.e. not systematically biased), and car has excess capacity to deviate from that estimate without dying on the road.

I'm using extreme caution; in my experience, even driving 10 below doesn't have much of an effect; perhaps it has saved me 3%. Otherwise I am consistently getting well below the initial projected percent on arrival. Check out the attached image.

I have done many long road trips, coast to coast USA, all over the Western US, and have driven about 150k miles now in the last 4 years in Tesla Model X, 3, and now Y. A Better Route Planner is a very helpful tool for planning, but I have found that the onboard car trip planner is reliable to +/- 10%. Often times it's within only 2%, but worst case, in all weather conditions, even in winter with the heat on, and snow, I don't think I ever arrived with less than 10% LESS than what the car predicted.

I will definitely look into a better trip planner app... My target concern isn't necessarily the actual rage, but trusting that the computer can accurately predict when I can leave :-/ and its never been accurate after 7k miles.

Also, overall wind is usually no higher when 10 mph in either direction, but even when I'me traveling with the wind I'm getting those high Wh/mi. I understand that I may be over reacting, but I new to the world EV and really appreciate all these perspectives !

 

[holmgang]

View attachment 534666
!

the linearity of those graphs rules out any 2nd order noise... your baseline consumption must be way off from the projection. are you driving quite fast? windows fully down? AC fan on full blast? cargo box on the roof? constant headwind for all of 120 miles?

if thats what youre always seeing, it is a bit worrying. i have same lifetime distance covered as you and the computer has always proven accurate, across broad range of routes and conditions.

curious what your speeds were and the consumption measured by the computer? i10/i35 i remember you can maintain going 80/85 forever

 

[arghx7]

There's nothing wrong with your car. EPA estimates are done with no accessories on at speeds slower than 70mph.

 

[andyemm]

the linearity of those graphs rules out any 2nd order noise... your baseline consumption must be way off from the projection. are you driving quite fast? windows fully down? AC fan on full blast? cargo box on the roof? constant headwind for all of 120 miles?

I wish any one of those reasons could explain it, lol. Alas, I'm following the speed limit (Max of 75 mph) on cruise control. As for headwind, I've gotten this performance consistently despite direction and wind speed; it may be Texas but it's not really all that bad all the time. During each trip (I've taken several), consumption measured by the computer is consistently 350-360 wH per mile.

There's nothing wrong with your car. EPA estimates are done with no accessories on at speeds slower than 70mph.

There are no Accessories, and I'm not comparing to EPA. In my original post, I am comparing to LikeTesla's range table, an aggregation of expected range based on model and speed; read below.

According to TesLike's Range Table, at an average speed of 75 mph (average interstate speed limit in Texas) with the P3D+ 20 inch wheels, I can expect to travel 252 miles.

 

[AdamVIP]

Hello all! I'm new to the TMC forums and Performance Model 3 (with 20 inch wheels) ownership. I've been struggling with the range of my vehicle, as the computer never seems to accurately calculate expected energy consumption during long range trips; even after over 7,000 miles on the odometer. Using the data from the Tesla Range Table at Teslike.com and self procured data from recent trips, here are my following assessments:

According to TesLike's Range Table, at an average speed of 75 mph (average interstate speed limit in Texas) with the P3D+ 20 inch wheels, I can expect to travel 252 miles. Assuming that the battery's capacity is 75kWh, I can solve that the average Wh per mile is 297. (75,000Wh / 252).

During my last 164 mile trip, the navigation calculated that I should arrive with 22% battery capacity while starting with 91%. Assuming that the computer expect to use 69% of the battery or 51.75kWh (75kW of total capacity x 0.69), I can then calculate that the computer expected to average out at 315.549 kW/mi. (51,750Wh / 164).

Okay, now for real world results with an exterior temperature of 75*F at a top speed of 75 mph: 355 Wh / mi, which in theory would have knocked me down to 14% (164 miles * 355 = 58.22 kWh, 58.22 kWh / 75kWh = 0.776 battery capacity lost, subtracted from 91%), but in reality somehow knocked me down to 10%. I am *Not* driving aggressively and was using cruise control for the entirety of my drive.​

Observing this data, I'm finding that my real world energy consumption is 1.125 times more than the computer is expecting to draw, and 1.195 time more than the data from TesLike. I quite literally cannot trust the navigation's estimated capacity upon arrival, especially on trips with a charge in-between as it is quite unpredictable. On my 250 mile trip to my family's home, If I were to leave when the navigation system says I can, the battery would surely die far before my arrival.

I am concerned because this is not the battery performance / trip planning accuracy that I've witness from other Teslas owned by friends. However, Tesla's diagnostic team is telling me that the batter is functioning as expected.

I'm really not sure what to do, if this is actually normal, or how to go about it when Tesla is telling me that everything is fine. Does anyone have insight into this? or have a similar experience yourself?

Driving my M3P I used to average like 298 Wh/mi average but now Im driving faster with less people on the road and Im up to about 305 Wh/mi average. I think you are pretty well in the norm. Even though Texas speed limits allow for 75 the range isnt based on 75 mph. also any hills can kill range. I drive out of and into a valley everyday and I never save enough on the down to make up for the extra on the up.

 

[Zcd1]

I was told by Tesla service that it does adjust to driving habits over time though.

This is not entirely accurate. The projected range on any trip starts based on the speed limits and elevation changes factored into the Google Maps' route, and adjusts as the trip progresses. The projected range/end of trip SOC can go up or down based on the way you drive DURING THAT TRIP.

Check out the attached image.

I've seen energy graphs just like that one in my car - when I'm driving 75+mph on the freeway over long distances.

To make a 250-mile trip with no charging would require about a 65 mph cruising speed, based on my experiences over 16K miles in my M3P.

Edited to add: That said, if there's a Supercharger along your route, the trip would likely take less time overall if you stopped for a quick Supercharge that enabled making the trip at 75-80mph.

 

[ryanjm]

This may not be helpful at all but because 350 does seem about 10% or so too high under those conditions (I have a P3D+ too and have done a few road trips), here’s a left-field thought: is it possible one of your brake calipers might be off or stuck and ever so slightly rubbing against the rotor?

 

[Feathermerchan]

I have a P3D+ also and first thing I did was ditch the 20" wheels and summer tires for 18" forged and MXMV's. Not the same performance but much better range and I can drive below freezing. My range estimation in the car is usually pretty accurate. My battery state is displayed in %.

Oh and your consumption sounds about right in terms of WH/mi based on your configuration. I run about 46 psi in my tires.

 

[ElectricIAC]

I’ve been running 48psi all around on the stock 20’s (Michelin AS3+) and typically see 300-450wh/mi @75-85 depending on headwinds.

 

[_TTT_]

There's nothing wrong with your car. EPA estimates are done with no accessories on at speeds slower than 70mph.

This. I've already been down this road with Tesla service and my M3P with 20" wheels. Currently at 17k miles, average of 355Wh/mi lifetime and I don't drive aggressively either. Here's what service had me do:

Pick a flat stretch of highway and a 20 mile route on a dry day around 70F. Turn off climate control. Drive the route in both directions back to back at 55mph and observe the energy consumption. Mine was 240Wh/mi.

But as soon as I drove "normally," it shot back up above 300Wh/mi. I have found that turning off climate control can make a big difference and lowering speed makes the biggest difference.

At the end of the day, I concluded the following:

1) EPA ratings are way off for M3P with 20" wheel/sticky tire combo if you are driving normally
2) Onboard computer cannot calculate the correct energy consumption. Especially noteworthy for long trips...you have to build in buffer yourself.
3) Should I buy smaller wheels with more efficient tires? I chose not to, but this is your only option for increasing your range beyond turning off HVAC and other accessories.

Sorry to be the bearer of bad news. If you decide to get the smaller wheels, I'd be interested to know how your range is affected.

Otherwise, enjoy the car