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Speed vs efficiency data

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David99

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Jan 31, 2014
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This is a graph showing the efficiency vs speed driven. It's approx 25k miles of data from my Model Y Performance.
100% efficiency is considered 'rated range'. Basically the energy consumption that would give you the range the car shows.
I think the graph is helpful to understand how speed affects range.

The dip at 25 to 35 is most likely due to lack of data.
 
Interesting. It seems that the realistic ideal speed on the highway is 65. For some reason I always thought you could inch up towards 69 before seeing the big dip that would allegedly start at 70. Thanks. This is really helpful. Now I know that I’ll be lucky to get 85% of the range on any given long trip. I always thought it was better than that!
 
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This is a graph showing the efficiency vs speed driven. It's approx 25k miles of data from my Model Y Performance.
100% efficiency is considered 'rated range'. Basically the energy consumption that would give you the range the car shows.
I think the graph is helpful to understand how speed affects range.

The dip at 25 to 35 is most likely due to lack of data.
Giid information, thanks!
 
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It’s really more of a misnomer that nothing reaches 100%..
I’d be interested where all the data comes from, is it TeslaFI or track my tesla?..

Anyway, it’s very hard to take a number like AVERAGE MPH, and extrapolate clearly or that precisely. Directionally, this is all probably accurate. Higher speeds, lower “efficiency”.. lower speeds, SOMEWHAT higher efficiency.

But, for example. We’ve seen many many tests, either early on or since M3 launch that the highest “efficiency” is ~ 31-33 mph. A LR M3 can do economy of ~ 115w/mile. That would yield about 600+ miles of range. Traveling constantly and flat without significant excess weight other than TWO occupants.

That is technically 210%+ efficiency. i know from having done speeds like that on purpose that I can get the level of economy from the battery and motors.

Having done many tests on I5 traveling when there are no significant elevation changes, doing 30-60 mile runs, resetting trip computers and measuring battery % and range, watching the onboard measurements I can get 110% efficiency at ~ 65 mph and roughly 100% at 70 mph. but with acceleration, hills, slow start stop start this all changes and overall it drops to ~ 90% efficiency. On these longer trips I also tend to travel quite a bit at 80+, averaging somewhere between 72-75 over hours at a time.

As an example if I drive from home to town 1.3 miles each way and back again, no elevation changes.. moving the mass in reverse, then starting forward, then coming to a stop, then moving all the mass again up to 33 mph, is about 40% efficiency, driving at 33 mph (with total average of 25) is ~ 175% efficiency. Overall, it’s about 115% at the end.

So, while these mph numbers are averages, there probably aren’t enough captured trips, of long enough duration that were really JUST at 30-35, or 35-40, etc to make the real efficiency at those speed ranges more precise and evident of what the abosolute efficiency is at that fairly specific speed.
 
Helpful data. Is good for any prospective buyers to be aware of.
So many of the negatives of the electric cars are blown out of proportion but the lack of efficiency at normal highway speeds is one that actually gets very little mention and as an owner one I find significant.

Who drives 65 or under on the highway when there is no traffic?

Is the main reason I don't personally achieve rated mileage, I drive mostly all highway. ICE cars are the opposite being most efficient at highway speeds and terrible for the city stop and go. I knew of this in advance so not disgruntled at all about it. With my high mileage highway commute I always achieved better than EPA mileage with ICE cars.
 
Helpful data. Is good for any prospective buyers to be aware of.
So many of the negatives of the electric cars are blown out of proportion but the lack of efficiency at normal highway speeds is one that actually gets very little mention and as an owner one I find significant.

Who drives 65 or under on the highway when there is no traffic?

Is the main reason I don't personally achieve rated mileage, I drive mostly all highway. ICE cars are the opposite being most efficient at highway speeds and terrible for the city stop and go. I knew of this in advance so not disgruntled at all about it. With my high mileage highway commute I always achieved better than EPA mileage with ICE cars.
ICE cars for years have been engineered with output and transmission ratios to be most efficient and leveraged at 55 mph.. I think it might have crept up slightly in the past maybe decade..

but most ICE cars will still be slightly MORE efficient at 40-50 mph - there are too many ICE cars and variables, size, shape, cd, load, etc. to come to a specific figure, but it’s not just a line up to 55 and then down, it’s usually a line up to ~ 40, and then slightly down to 55, then steeper decline.

I always got better than EPA on my ICE cars and many high performance ones, but this is certainly due to my driving style..not hard acceleration, lifting off to decelerate instead of slamming the breaks - as many do - trying to maintain constant speed, possible following, not always just sitting out in front in the left lane but have preferably one car ahead…

I think all these driving habits carried over well to an EV where de-celeration is regenerative and not slamming the GO pedal is more efficient than always toying with torque. I’m happy with the results and process.
 
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Well those ICE cars certainly don't lose 25% of range sitting at 75 - 80 on the highway.

Mostly have owned 6 cylinder ICE and some of those I think do a little better at the higher speeds proportionately to their rated mileage than smaller less powered cars do but yes I agree your personal driving style is a huge factor for both ICE and EV.

Very happy with my EV and zero regrets ust stating my experience.
 
I do.

Lifetime Wh/m is 227 at 19,000 miles for a 2022 MSLR. Speed doesn't excite me, but acceleration and pulling Gs around the corner does. Unfortunately that heavy car pales to my last Corvette in the corners.
Just poking fun ; but in all seriousness the highways around me in MA can get some aggressive drivers and just to not be a road hazard you often need to at least maintain 70.
I believe in the only drive in the left lane when passing or going at go directly to jail speeds as they practice in Europe personally and that theory needs all traffic to maintain a certain speed to work well.
 
I do.

Lifetime Wh/m is 227 at 19,000 miles for a 2022 MSLR. Speed doesn't excite me, but acceleration and pulling Gs around the corner does. Unfortunately that heavy car pales to my last Corvette in the corners.
That’s a very good example of a metric to use… since 227 is HIGHER efficiency than EV MPGe would indicate, so overall you’re OVER 100% for the lifetime of the car..

Mine is 230, slightly better in spring / summer slightly higher in winter. Overall, 230 w/mile whereas the car is rated at I believe 245-250 w/mile.
 
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Just poking fun ; but in all seriousness the highways around me in MA can get some aggressive drivers and just to not be a road hazard you often need to at least maintain 70.
I believe in the only drive in the left lane when passing or going at go directly to jail speeds as they practice in Europe personally and that theory needs all traffic to maintain a certain speed to work well.
As long as you stay in the right lane I feel safe even at 60