Impact of cruising speed on range

[en1gma]

Wondering what everyone’s real world experience is regarding the impact of driving at 80mph vs 70mph on the motorway.

As posted previously, my Macan 4 is due in March and it will be my first full EV. Currently have a PHEV BMW X3 30e hybrid which is pretty much petrol-only at cruising speeds.

And, yes, the motorway speed limit here in the UK is 70mph, but...

Assume all other variables are excluded/have no affect (weather, use of AC, load, etc), it’s just the impact of cruising speed I’m interested in.

Thanks in advance!

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[SergeyIndy]

I would say material impact with really not getting quicker to the destination.

EVs are super inefficient at highway speeds and when you add cold dense air and rain then you are really losing range quickly. Cd of .25 is pretty good but will not help you much at 80mph. I can give you my Taycan example where my best real-world range is 275 miles under ideal conditions (not highway), then I drove on a highway at near 0C at 80 mph in light rain and I could barely make 160 miles with .22 Cd. I think if I would be going at 70 mph, I would expect 20-30 miles more.

 

[Yves]

400km in 9month’s of the year 300km the other 3 … that is from 80%
at 70 miles you will be at around 20kwh/100km when the conditions are ok …

 

[W1NGE]

Wondering what everyone’s real world experience is regarding the impact of driving at 80mph vs 70mph on the motorway.

As posted previously, my Macan 4 is due in March and it will be my first full EV. Currently have a PHEV BMW X3 30e hybrid which is pretty much petrol-only at cruising speeds.

And, yes, the motorway speed limit here in the UK is 70mph, but...

Assume all other variables are excluded/have no affect (weather, use of AC, load, etc), it’s just the impact of cruising speed I’m interested in.

Thanks in advance!

Depends on the motorway conditions and if you expect recuperation or not.

EVs don't perform their range best at a constant motorway speed where there is little or no opportunity to recuperate any energy back into the battery.

Rather than enable recuperation leave it off and you'll find coasting helps overall efficiency in these conditions.

Hard to be precise but travelling at a higher constant speed will logically use more energy.

 

[joeev]

State of Charge channel on YouTube did this exact test:

 

[W1NGE]

State of Charge channel on YouTube did this exact test:

Excellent and confirms what I thought (bizarre outcome otherwise)

 

[en1gma]

State of Charge channel on YouTube did this exact test:

Thank you for sharing! Very thoughtful and clear video. No unnecessary hyperbole BS either, for a change in a YT video!

 

[TomekGnomek]

Wondering what everyone’s real world experience is regarding the impact of driving at 80mph vs 70mph on the motorway.

From my experience this is not the right way to look at this problem.

Key to driving fast is charging fast. It's much more important to have good infrastructure of fast chargers and car that can handle fast charging well.

Macan and it's Route Planner handles this job very well so you just forget about it and enjoy driving. TBH I rarely go below 30kw/100kms on highways which does not give you much range.

 

[skshimer]

I drove a Model S for 5 years. Like many first time EV owners I worried about total range on long trips. After a few 2500 mile trips I realized it was more about how long we each wanted to drive before stopping, eating, etc. while charging. Then I would just chart out 10% over the speed limit and look for chargers. With access to both EA and Tesla (plus a myriad of others) it is easy. Now I just start with 100% SoC and find the furthest SC on my route where I can arrive with 15% charge and work any other details from there. Have fun.

 

[en1gma]

Key to driving fast is charging fast. It's much more important to have good infrastructure of fast chargers and car that can handle fast charging well.

This is what the video posted earlier in this thread alludes to. It also identifies the kind of cost impact this approach incurs - again, only an indication not a definitive statement.

As I said in my original post, I just wanted an indication of impact of a bigger cruising speed. I fully appreciate it’s much more nuanced than that!

 

[CHP]

Depends on the motorway conditions and if you expect recuperation or not.

EVs don't perform their range best at a constant motorway speed where there is little or no opportunity to recuperate any energy back into the battery.

Rather than enable recuperation leave it off and you'll find coasting helps overall efficiency in these conditions.

Hard to be precise but travelling at a higher constant speed will logically use more energy.

I like to think this is a common assumption but there is no Perpetuum mobile

1) Energy consumption increases exponentially with speed due to aerodynamic drag. I would like to see figures for how many miles Taycan GT can run at top speed. Top speed in EV's is a gimmick. Yes, the effortlessness is intoxicating but requires self restrain on longer drives.
2) Recuperation is not 100% so maintaining speed without braking will result in lowest energy consumption.
3) Quick charging is only from 10 to 80%. First stint (100% charge) 80-90%, app. 60-70% thereafter (some misfortune with chargers still under construction, out of service, power failure or blocked by ICE, I use 20% instead of 10% on longer distant drives). I managed 38 kWh/100 miles at 70 mph under ideal conditions (Macan 4, 20 inch wheel, 20 degree celsius)

In comparison to ICE, EV's excel in low speed traffic and stop and go. They are much more efficient as they recuperate braking into energy. An ICE SUV first needs to bring 2.5 tonnes to 30 mph only to stop to 0 after only a few hundred meters at a red light. All this energy is wasted.

 

[dbsb3233]

The 19% less MPK (mi/kWh) at 80 vs 70 in Tom's video is fairly consistent with what we see too. We've done 4 long (2000+ mi) road trips in ours now with mostly 75-80 MPH speed limits, but also some 65-70 mixed in. Just the difference between 75 and 80 probably costs around 10%.

Although how he got 3.7 and 3.0 MPH is a bit of a mystery. We average about 2.8 MPK overall on our road trips in the Macan. And that's the better-mileage RWD rather than the 4. Although we do have the bigger wheels (unfortunately). And a few of those have been during colder months. But even the summer trips were <3.0.

 

[CHP]

The 19% less MPK (mi/kWh) at 80 vs 70 in Tom's video is fairly consistent with what we see too. We've done 4 long (2000+ mi) road trips in ours now with mostly 75-80 MPH speed limits, but also some 65-70 mixed in. Just the difference between 75 and 80 probably costs around 10%.

Although how he got 3.7 and 3.0 MPH is a bit of a mystery. We average about 2.8 MPK overall on our road trips in the Macan. And that's the better-mileage RWD rather than the 4. Although we do have the bigger wheels (unfortunately). And a few of those have been during colder months. But even the summer trips were <3.0.

Altitude differences does have quite an impact (daily school run up and down the hill). More so, driving style. On a 10 miles city drive home from dealer I managed significantly less than 3 (excited, new car) whereas technician collecting car (red circle of death) managed 4.0 on way back.

 

[ckfilm]

I've had my Macan Turbo for 14 months and have driven 19,500 miles in that time period. I routinely drive between Los Angeles and La Quinta, California (140 miles each way). As a matter of practice and after getting to know the DNA of the car and its capabilities, for clear highway /motorway driving (and with re-gen off, which I only use in heavy traffic or city driving)... with a state of charge of 80% and cruise control set to 75 - 77 miles, the 140 mile trip will usually consume 55% of my power, leaving me with 25% of power left upon my arrival. Weather and extreme head winds (common for Palm Springs) will play a factor. I will easily lose 5 to 8% of power over my 140 mile trip, leaving me with 20% (50 to 60 miles of range) upon arrival. Overall, for every 20% of power used and at speed set between 75 to 77 miles per hour, I am getting 55 to 63 miles of range.

 

[USMA81]

In the comments on the State of Charge YouTube video, I posted:

”It’s physics. The drag force is the square of velocity, all else being equal. So take the ratio of the increase in speed, 80/70 =1.1429. And square it, 1.1429 x 1.1429 =1.306. So 345 miles (@70) theoretically should give 345/1.306=264 miles range at 80. The fact it did better than 264 likely is due to other, real world factors of the design or driving conditions that might have reduced drag a bit vs theory (% of time vehicle was in a draft and effect of any draft, position of rear spoiler, consistency of holding speed, differences in winds, etc.).”

After a year with the Macan, I ignore driving slower to save enery and just plan my stops accordingly.

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