True Driving Range

80mph is much higher than what Tesla used for EPA testing. Just like at 80mph you will never get your rated MPG in an ICE.

Tesla has a calculator online, I think it's right on the main page

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Model S | Tesla Motors

Most of the way down, you'll find it "range per charge"

chucks said:

As with an ICE car, a Tesla's driving range is a function of many things, including speed. On a recent 8-day trip, my first long range trip in my S, I noticed that the predicted driving range did not match what my odometer displayed as I drove. On a flat highway using cruise control to maintain a steady 80mph, I computed that I was achieving about 80% of the predicted range. Has anyone taken samples at other constant speeds?

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Maintaining a steady 60/65 mph will get you closer to the predicted range in 'normal' driving conditions...

chucks said:

As with an ICE car, a Tesla's driving range is a function of many things, including speed. On a recent 8-day trip, my first long range trip in my S, I noticed that the predicted driving range did not match what my odometer displayed as I drove. On a flat highway using cruise control to maintain a steady 80mph, I computed that I was achieving about 80% of the predicted range. Has anyone taken samples at other constant speeds?

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Sampling at a variety of speeds is tough due to the large number of variables. You'd have to hold wind, air temperature, humidity, road surface, battery temperature, tire pressure, and many more constant and do so over a sufficiently large distance to get statistically significant results. It can be done, of course, just not how I would want to spend a few days. As mentioned above, Tesla published a few samples on their site.

If you're getting 80% that's probably pretty good for 80mph given that drag increases dramatically over about 60mph.

80 mph needs more energy than 70 mph, but going at 60 mph uses even less energy to travel the same distance. The official numbers are always on the optimistic side. You have to drive very 'gentle' to be able to get the rated miles.

Once you had your car for a while you'll get a good idea how far it goes in reality depending on weather. Don't use Tesla's range calculator on their website. It's not realistic. It says my 85 would go 280 miles at 65 mph in warm weather. Not going to happen.

I had a chuckle when I read that OP couldn't get rated range at 80mph, especially when there is qualifier that he is aware that speed impacts range. Perhaps he should try 100mph to get the rated range?

Every mile increase in speed roughly increases the energy needed quadratically to cover the same distance. So if you use 10kwh to cover 5 miles at 50mph, so you will end up using 20kwh to cover the same distance (5 miles) at 100mph most of it due to wind resistance and to a lesser extent due to rolling resistance. The effect is pronounced at higher speeds and less at lower speeds.

chucks said:

As with an ICE car, a Tesla's driving range is a function of many things, including speed. On a recent 8-day trip, my first long range trip in my S, I noticed that the predicted driving range did not match what my odometer displayed as I drove. On a flat highway using cruise control to maintain a steady 80mph, I computed that I was achieving about 80% of the predicted range. Has anyone taken samples at other constant speeds?

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Well, this confusion stems from the part where Tesla uses rated range to express remaining battery capacity. That's not the remaining range using your current driving conditions. You have to use the energy graph to get projected range information, but since it varies a lot depending on your driving, you have to play with the settings to get a good estimate. If your navigation is set up, you can also use the trip information to see how far you are deviating from the range estimates.

For reference, see:
Model S Efficiency and Range | Tesla Motors

http://www.evtriplanner.com and look at Rated Miles (RM) to see how the variables affect your effective range. Or, if that's too technical, the Tesla website does have the pretty cartoon version of it per above.

- K

I may be oversimplifying it but I got tired of the rated range being so optomistic so I changed my display to show % battery and then predict mileage as a little over twice battery % to be conservative. So at 90% battery instead of the rated 240mi range I assume its more like 180 + a little more or around 200mi.

Given that the car has your driving history, it should be trivial to compute and show you your "likely" range at any given moment. Tesla has made a decision to not provide this information to us.

And here I thought it was hard to get less than rated range

musicious said:

I may be oversimplifying it but I got tired of the rated range being so optomistic so I changed my display to show % battery and then predict mileage as a little over twice battery % to be conservative. So at 90% battery instead of the rated 240mi range I assume its more like 180 + a little more or around 200mi.

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That's pretty clever actually and off the top of my head probably about what I get too. Judging from your numbers you are a spirited driver .

tstafford said:

That's pretty clever actually and off the top of my head probably about what I get too. Judging from your numbers you are a spirited driver .

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Thanks I figure it helps to plan a trip cause if the miles are within twice the battery % then I know I have enough to get there.. I was being conservative tho I do like using climate and acceleration In the winter temp I figure I just wont add the extra so like 90% =180mi range