It’s worth noting that he recently did the same test, with similar temps, in the EV9 (which is also super inefficient on the highway), and got over the EPA range. IIRC most of his range tests exceed EPA numbers.
Comment on Tesla Cybertruck gets less than 80% of advertised range in YouTuber’s test
atmur@lemmy.world 5 months ago
I hate Tesla and especially the Cybertruck as much as the next guy, but this was a highway test and that sounds like a completely normal result.
I own a Bolt EV which is rated for 259 miles of range. On the highway, that’s more like ~220. That sounds bad, but the other side of it is that I get ~300 miles of range during my normal work commutes through the city. This is just how EVs are, the estimated range is based on a mixed test. EVs are backwards compared to ICE, you’ll get ~20% less range than the EPA estimate driving highway speeds and ~20% more doing purely city driving.
TheIllustrativeMan@lemmy.world 5 months ago
andrew_bidlaw@sh.itjust.works 5 months ago
Why highways are worse than city streets? Highway doesn’t have traffic jams, frequent stops when you just burn fuel\electricity to move a little further. It’s just supporting the momentum of a car. With more than one gear it’s trivial.
Maybe I don’t understand something about e-cars, but from my experience I have wasted like 30% less of fuel just driving on highways from city to city for the same distance I drove in town.
overzeetop@lemmy.world 5 months ago
In traffic, the largest reduction of efficiency comes from accelerating and the braking. You use energy to start moving (proportional to m V^2) and then you dump that energy into heat in your brakes to stop. The second comes from idling where you use energy to keep the engine rotating. As others have mentioned, EVs use regenerative braking so a substantial portion of the energy used to slow and stop the car is used to recharge the battery. EVs have no need to keep an engine running so unless you’re running the a/c there are minimal demands on a stopped/idling EV.
On the highway, you have the internal friction in the drivetrain to overcome, the constant deformation of the tires, and - most importantly - wind resistance, which is proportional to cd x rho x V2.
Cd (drag) and rho (air density) are low, but that V (speed) squared means driving at 75mph incurs 25x the energy use as driving at 15 mph. An EV gets no sage harbor here - plowing through a fluid (air) is essentially the same work.
To give you a sense of numbers, my vehicle (F150) gets less than 10mpg the 5 miles to my local pool/gym. The speed limit is 25 mph but there are stop signs every block or two. Lots of braking loss. On back roads with gentle curves and a 45 mph limit I get close to 30 mpg. That’s the sweet spot between overcoming transmission friction and air resistance. On the highway at 60 mph I get 22-23 mpg. At 78-79 mph I get 19 mpg. These are all generally on flat stretches using the 6 min average on my dashboard.
(Sorry for the long post…I’m an engineer and mechanical efficiency and aerodynamics are my happy place)
madcaesar@lemmy.world 5 months ago
Ah so actually it’s not that ICE vehicles are more efficient at highway speeds, it’s that they are just SO MUCH worse in city driving that it only seems that way.
Interesting, I never thought about it that way
abhibeckert@lemmy.world 5 months ago
It’s both. Nearly all ICEs are specifically optimised to cruise at 50mph. Anything more or less will significantly reduce your MPG.
But yeah, slow speeds are really inefficient in an ICE.
overzeetop@lemmy.world 5 months ago
Any braking without energy recovery is wildly wasteful. Public transit (busses, trains) are fucking terrible wastes of energy due to their large mass and frequent stops. Hybrid and/or electric busses are, in this respect, potentially far superior to their diesel counterparts. I’m not a train person (engineer…train…haha) but I don’t think even the all electric trains use regenerative braking and there are few battery powered trains in service.
I’ve spent the last year altering my driving habits when I can. I try not to be an asshole when others are around/in traffic, but when I’m not pressed I will coast to a stop as much as possible (esp uphill) and use hills to gain momentum. Over 6000 miles, I’ve raised my overall mpg around 18%.
andrew_bidlaw@sh.itjust.works 5 months ago
Don’t be. I’m happy to learn.
coaxil@lemmy.world 5 months ago
Don’t apologise, this was a great post!
WhiskyTangoFoxtrot@lemmy.world 5 months ago
So, in other words, the only things EVs are good at are things that public transit would be even better at.
abhibeckert@lemmy.world 5 months ago
Consider a typical afternoon commute for a parent - you go from work to your kids school to some after school activity (different destination every day) to a few grocery stores then back to the after school activity and then finally home.
Sounds like it’d take about 5 hours with public transit, especially since for some of those you’d literally be getting off the bus stop, then 5 minutes later be back at the bust stop waiting for the next bus. You’re not allowed to just let the kid run off to soccer practice these days - a parent has to actually go in and sign them in. And they won’t let the kid wait at the bus stop either, they will only release the kid from their care when the parent comes in to pick them up.
overzeetop@lemmy.world 5 months ago
Not quite. EVs can still do door to door transport, are faster portal to portal, and have a vastly more diverse infrastructure, including the ability to (at least in a limited extent) traverse areas without track or road infrastructure. Public transit is still better, especially for rail, in reducing energy losses due to wheel deformation, reduction of human fatigue and dependence on attentiveness, and in some cases station to station speed and net air resistance per passenger mile. Since this is technology instead of fuckcars, it seems reasonable not to circlejerk too much.
NeatNit@discuss.tchncs.de 5 months ago
only things
Just to list a few things EVs are good at that public transit isn’t:
- private transportation that isn’t long-distance, as abhibeckert@lemmy.world’s comment describes
- less total energy consumption
- no awful emissions for everyone around you and for yourself, so e.g. inside a parking structure it wouldn’t be so awful to breathe
- anything you can’t do on public transit, such as:
- moving small furniture
- taking your pet to a vet, or anywhere else for that matter (it might be allowed on public transport in certain cases but it would still be much more of a hassle difference compared to normal human taking public transport vs personal car)
- it’s still good at driving on highways, it’s just better at driving in other scenarios.
I don’t want a car and I use public transportation, couldn’t let that fly though. EVs have their place. Not to mention electric buses are EVs and are even a better riding experience.
- private transportation that isn’t long-distance, as abhibeckert@lemmy.world’s comment describes
atmur@lemmy.world 5 months ago
Traveling at high speeds just takes a lot of power regardless of fuel, but ICE cars are so inefficient in city driving it makes highways look good in comparison. 25-50mph might be more efficient, but every time you brake that kinetic energy is turned into waste heat, totally negating the benefit of driving slower.
EVs on the other hand have regenerative braking systems. Rather than using friction to slow the car down, they just use the motors by applying resistance to the wheels. The kinetic energy is used to charge the battery while slowing the car down. You get the benefit of slower speeds without much braking loss, so this is where EVs shine.
andrew_bidlaw@sh.itjust.works 5 months ago
That sounds really sweet for a street usage.
hperrin@lemmy.world 5 months ago
Frequent lite braking allows the regenerative brakes to do all or almost all the work, meaning you recover a good chunk of the energy you’re using in city/stop and go traffic.
Infrequent braking or hard braking (which requires the service brakes) means less energy recovered, so shorter range.
asret@lemmy.zip 5 months ago
Braking does not increase range. Regenerative braking reduces the losses involved, it doesn’t eliminate them. Your last sentence makes it sounds like not braking enough will lower your range - that isn’t the case.
andrew_bidlaw@sh.itjust.works 5 months ago
Hmm. So it’s a sneaky little argument for EVs for an in-city use? I wonder why no company screamed about it through a loudspeaker. If that’s so, it’s a killer feature for most drivers
hperrin@lemmy.world 5 months ago
It was one of the main selling points of the Prius. Great gas mileage, especially in city driving.
QuaternionsRock@lemmy.world 5 months ago
If I’m not mistaken, the much more important element is air resistance. The power-efficiency ratio of electric motors is nearly constant, meaning the energy usage per unit distance is nearly the same at all speeds, but there is more air resistance at high speeds.
capital@lemmy.world 5 months ago
Excuse the meta conversation but why are people downvoting what seems to be an earnest question?
Lighten up and just answer the question.
vithigar@lemmy.ca 5 months ago
In addition to what atmur said, EVs don’t have the baseline inefficiencies an internal combustion engine requires just to keep itself running. ICEs waste a huge amount of energy just running, which gets lost as heat, vibration, and noise. EVs have the advantage of being able to run just as much as needed, so you don’t throw away huge amounts of energy at low speeds.
The efficiency curve of an ICE vehicle generally peaks somewhere around 70-90km/h, due to a combination of wasted energy at low speeds and gearing ratios. EVs peak much lower, generally in the 35-55km/h range. This is due to not having the low speed overhead of an ICE, but still being subject to high speed inefficiencies like rolling resistance and drag.
turmacar@lemmy.world 5 months ago
In fairness there is some baseline inefficiency in that they have to keep the battery pack in an acceptable temperature range. How much of an inefficiency that is depends on outside factors, but it’s there.
nixcamic@lemmy.world 5 months ago
Also this test was at 45⁰ C? That is not a normal temperature for most people.
flyingjake@lemmy.one 5 months ago
It’s the New York Post, temperature would be a chilly 45F for their American audience
nixcamic@lemmy.world 5 months ago
Ah that’s a much more normal temperature but cold enough that it would start to affect the range also no?
gamermanh@lemmy.dbzer0.com 5 months ago
Not really, my card range doesn’t really start to be hurt until you’re in sub-freezing (32F) conditions
I think when the weather is 45 instead of the more normal 65 temp for when go to work the average battery drain % difference is 2 or 3, which even on my leaf with 155 miles of range isn’t much
nbafantest@lemmy.world 5 months ago
It’s farenheit, Its winter/cold in America right now
weew@lemmy.ca 5 months ago
also, the EPA test cycle for highway has a maximum speed of 60mph, with the average below 50
pythonoob@programming.dev 5 months ago
Yeah this is what it’s like with my mach e as well. I have an extended range and I get 300ish miles town/city but on the highway probably 240. So realistically I charge every 190-220 miles on long road trips with the 80% fast charging stations.
cultsuperstar@lemmy.world 5 months ago
And EVs and hybrids have regenerative braking so that does some recharging of the batteries. It’s not going to be stellar, but jn stop and go traffic, it could definitely had some miles to range. There’s a lot less stopping on highways.
chiliedogg@lemmy.world 5 months ago
Regenerative braking isn’t magical. It doesn’t add range. It reduces range lost by stopping. Conservation of energy is still a thing.
If you were to drive any speed uninterrupted until the vehicle died, then attempted the same drive with stops every mile, the vehicle wouldn’t make it to the end.
piecat@lemmy.world 5 months ago
Semantics. Regenerative braking adds miles of range compared to those without.
chiliedogg@lemmy.world 5 months ago
Yes, but it’s unrelated to highway versus city performance in electric/hybrid cars.
Driving under highway speeds is almost always more efficient due to wind resistance. But for ICE cars without regenerative brakes the losses from braking and idling hurt enough to give the illusion of freeway efficiency.
And the reason actual highway speed versus the estimates on the sticker are often so far off with ICE cars is that the test is based on 55mph max highway speeds with an average speed of 48mph. Meanwhile the speed limits on all the freeways near me are between 75 and 85, making actual performance way, way worse.
GaMEChld@lemmy.world 5 months ago
This is true, but it’s neglecting one variable that does complicate the math slightly. There is greater air resistance at highway speeds. IIRC at 60mph 50% of your power is lost due to the air resistance.
So yes, if we lock the speed to a fixed value and compare them, then regenerative of course doesn’t increase the range more than not stopping at all. But that’s the nuanced gap in the discussion where misunderstanding is going to reside. That’s why you two are on different pages. Someone is assuming equal air resistance (speed), and someone is assuming a comparison of average city miles vs highway miles.
Neither is necessarily the ONLY way to look at it. It’s all relative.
qjkxbmwvz@lemmy.sdf.org 5 months ago
Important to note though that air resistance is nonlinear — it uses less energy to get from A to B slowly than quickly.
laurelraven@lemmy.blahaj.zone 5 months ago
It’s not only not “not stellar”, it’s the reason hybrids and EVs have higher city miles than highway. Acceleration takes a lot of energy compared to maintaining speed, and regenerative breaking recaptures most of that for use next time you take off.
It’s why hybrids can increase fuel mileage so much without being plugged in. It’s huge.
If you’re ever driving an EV that has the option to see real time flow of watts (with numbers, not just graphics), watch what it does while taking off, coming to a stop, and cruising at speed (both slower city speeds and higher highway speeds). You’ll probably see fifty to a hundred plus kW flow either direction while speeding up and slowing down, and under five while cruising
Soggytoast@lemm.ee 5 months ago
I have had my bolt, with new battery, for nearly 3 years. On interstate driving in summer I’m not sure I’d go beyond 180 miles, pretty sure 200 miles I’d be in turtle mode at least. Currently in winter I’m probably limited to about 160 tops.
machinin@lemmy.world 5 months ago
I wrote this in another comment, but Tesla has been known for a long time to game EPA numbers. Here’s an article from 2020 talking about it: insideevs.com/…/eletric-car-real-world-range-test…
Several get below their EPA numbers, but several cars also get higher. Tesla models all get significantly below their claimed mileage.
farcaster@lemmy.world 5 months ago
The insideevs article reports 239 miles for a Model 3 Performance while clicking all the way through to the actual source of the testing “Whatcar” reported 324 miles for a M3 LR. What car indeed.
I’m sure Tesla has been overly aggressive with the range numbers. Especially people in colder climates must be getting far less than advertised. But these low-effort articles are not the best of sources.