> Seems like it’s common across all EVs for the range to be inflated by around 20%, at least for freeway driving.

Most people speed on the freeway. Extra speed reduces range significantly.

IMHO comments like this are much more valuable with some numbers.

The linked figure[0] and associated paper report that efficiency peaks for EVs at around 20mph and then the cost per mile increases roughly linearly, by about 25 watt-hours when the speed increases by 10mph.

Please excuse the archaic units.

[0] https://www.researchgate.net/figure/ehicle-energy-economy-at...

The Tesla Roadster is an absolutely ancient EV.

This.

And it is true of petrol cars as well. In my old clunker going from 110 km/h to 120km/h is a 9% speed increase but nets about 15% extra fuel consumption.

Is this with the windows up or windows down...?

Yes.

And much more than one would intuitively think.

I just finished a long drive for summer vacation. Driving through Denmark (completely flat) at 130 km/h would absolutely wipe the battery, would be surprised if I managed even 350 km on a full charge. Driving over the mountains in Norway however, from 0m elevation to over 1000m and down again, at slower mountain roads (max 80 km/h), yielded almost 500 km on single charge.

I did not expect flat+high speed vs hill-climbing+low speed would be that dramatically different.

Air resistance is proportional to square of velocity. That goes up pretty quickly!

And the power required to move against the air goes up by the cube of speed (as you multiply the resistance times your speed itself.)

I imagine that regenerative braking has a role here too. When you're going downhill the battery can recharge itself to some extent.

Yes, but Tesla goes out of their way to advertise how fast their cars are, so you think they'd expect and factor for this kind of driving behavior.

graphs:

https://forum.abetterrouteplanner.com/blogs/entry/22-tesla-m...

https://forum.abetterrouteplanner.com/blogs/entry/9-tesla-mo...

Your 20% variation number seems valid for my EV.

I have a 2022 Nissan Leaf with 220 miles EPA range. I've found that this number is reasonably close to correct if one is driving under 60mph on country roads under moderate climate conditions. We live in Ohio and so I have actually done long drives like that to go to remote places to go camping. (There are, surprisingly, both L2 and fast chargers around in rural Ohio but you definitely need an app and need to check ahead of time.)

Speed matters because air resistance increases exponentially with speed, not linearly. Driving 60+, lots of stop and go, or using HVAC a lot will bring it down the range to as low as 180, but that seems like the worst range I've seen. That was driving ~75mph with HVAC on.

> Speed matters because air resistance increases exponentially with speed

No, drag is somewhere between linear and quadratic as a function of speed, not exponential. (Although it gets weird around the speed of doing.)

Heuristically, if you’re pushing through a cloud of particles, the number of particles you hit per unit time is linear with speed, and the impulse per particle is also linear with speed (because it’s the difference between your velocity and the particle’s initial velocity, times the particle’s mass, times a constant that’s around two for an elastic collision).

The rated range combines city and highway driving, and EVs get better city mileage due to the lower average speeds. So it would be expected that actual highway range (70+ mph) would be less than the rated combined range.

I used to have a Nissan Leaf. Same trip took 30% less charge, just because of the if was driving a behind a large track most of the way.

If you are driving close enough for drafting to have an effect, you are driving dangerously.

I have had the experience where drafting has happened it is was amazing the efficiency gains(I always watch real time usage).

The set-up is so dangerous but so tempting.