Agreed with you there. I just think it would have been good to under promise and over deliver. It was a bit eye opening to me when I have to supercharge my Model 3 MR for a 180 miles round trip. I have come to live with it, but just saying that missing the EPA range by 30% isn't that great when just about every other EV can come close to it.
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Rivian range to charge time is going to be an issue.
- Thread starter Assquatch
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thesmokingman
Active Member
The EPA number is at a speed of 56mph, I'm not sure you are getting that. If x car hits it's EPA rating at a greater speed, that means you're carrying a bigger battery than listed to get there. Thus the efficiency will be *sugar* but you don't know this and think omg it hit EPA numbers so impressed...
You are not understanding the point at all.
No one cares HOW a vehicle is hitting the EPA target. The well documented point is that other EV's are able to hit the EPA numbers while Tesla's continue to underperform in the same conditions.
I think you need to step back and read before hitting the reply button, because you're way off base here.
Candleflame
Active Member
Heavy cars will get a comparatively poorer EPA rating and exceed this easier in real life due to frequent acceleration and deacceleration in the test.
Rivian is on a 400V system, right? Is it feasible to get to 300kW using 400V architecture?
I'd generally assume that the base efficiency numbers behind the EPA scores are all calculated fairly and accurately, and I doubt that's why the Tesla miles seem to be shorter than the Porsche miles...
But after you calculate the efficiency numbers, there's a "adjustment" number you can calculate or apply. This is intended to account for times when you'll get worse efficiency because it's cold or it's windy or it's dark or it's wet or you're driving too fast, etc, etc. You can choose to either use 70% or to calculate it out, and you pick which method you use by which car.
Most everyone applies an adjustment of 0.7 (claim only 70% of the mileage you calculated)... But not Tesla. Tesla wants credit (reasonably?) for their heat pump and other things they've done to make sure the efficiency is consistent during different situations, and so they calculate their adjustment...and get ~75% [1]. So that's about a 5% "shorter mile" in ideal conditions. Tesla also lets you run the battery to basically dead, but then hides ~5% of that battery under "0 miles remaining/0%" to get you to not use it, while still letting it count to the advertised range.[2]
Combine those together, and you get tesla effective ("I'm not gonna hit 0% willingly, and it's a good sunny day, so the efficiency gains in the cold don't help me/hurt other cars") ~10% shorter mile[3].
I just wish numbers were more comparable and more accurate. More accurate would require the EPA to change the highway speed from ~56 (per above) to ~75. More comparable would be to get everyone to use the same 5-cycle methodology, and have a more useful/driver-centric definition of "empty"
[1] The Secret Adjustment Factor Tesla Uses to Get Its Big EPA Range Numbers .... I think it's higher now than when that story was originally written?
[2] Tesla saves more range at 0% than other EVs, test finds (Also an Edmunds story)
[3] The C&D feature at [1] above guesses the battery element is more like 20%. Testing at [2] didn't show THAT big a bottom-buffer past 0, but my guess is that the bottom buffer is used to also hide battery degradation. This would imply an larger actual difference in "mile length".
But after you calculate the efficiency numbers, there's a "adjustment" number you can calculate or apply. This is intended to account for times when you'll get worse efficiency because it's cold or it's windy or it's dark or it's wet or you're driving too fast, etc, etc. You can choose to either use 70% or to calculate it out, and you pick which method you use by which car.
Most everyone applies an adjustment of 0.7 (claim only 70% of the mileage you calculated)... But not Tesla. Tesla wants credit (reasonably?) for their heat pump and other things they've done to make sure the efficiency is consistent during different situations, and so they calculate their adjustment...and get ~75% [1]. So that's about a 5% "shorter mile" in ideal conditions. Tesla also lets you run the battery to basically dead, but then hides ~5% of that battery under "0 miles remaining/0%" to get you to not use it, while still letting it count to the advertised range.[2]
Combine those together, and you get tesla effective ("I'm not gonna hit 0% willingly, and it's a good sunny day, so the efficiency gains in the cold don't help me/hurt other cars") ~10% shorter mile[3].
I just wish numbers were more comparable and more accurate. More accurate would require the EPA to change the highway speed from ~56 (per above) to ~75. More comparable would be to get everyone to use the same 5-cycle methodology, and have a more useful/driver-centric definition of "empty"
[1] The Secret Adjustment Factor Tesla Uses to Get Its Big EPA Range Numbers .... I think it's higher now than when that story was originally written?
[2] Tesla saves more range at 0% than other EVs, test finds (Also an Edmunds story)
[3] The C&D feature at [1] above guesses the battery element is more like 20%. Testing at [2] didn't show THAT big a bottom-buffer past 0, but my guess is that the bottom buffer is used to also hide battery degradation. This would imply an larger actual difference in "mile length".
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Agreed it would be nice to have a set standard and requirements on test method and definition of range. The main issue that I have with Tesla's EPA number is that in can actually trigger range anxiety because the difficulty to come close to actual EPA numbers. I had purposely gotten a Mid Range instead of SR+ because I thought it would give me more than enough margin for what I expected as my longest work commute. Imagine the first time I had to enter my 180 mile round trip and was shown a negative % on the return trip. I am pretty much set on the EV path, so it's more of an annoyance to me than anything else, but imagine someone new to EV and their first experience with long range trip is that the car falls well short of its range capability. That could very well put range anxiety back into people's mind, which is what we don't want to do.
thesmokingman
Active Member
You don't care how it gets its EPA numbers even when its fake. Ok got it. There are a bazillion posts on this. The EPA numbers are frankly bullshit. The EPA doesn't even do the damn testing. Makers can put down whatever they want. And for ex. Hyundai got caught for BS numbers. Tesla's numbers are accurate as it can get. It will hit its numbers at the same speed as the EPA test. Replying that you don't care is frankly ignorant of the whole process around the numbers. Hell even the EPA wraps it all in a your mileage may very disclaimer, smh.
MXLRplus
Active Member
So far I'm seeing a bit more than EPA range (293 hwy) in the 2022 R1T w/21" wheels at 70 mph, about 315 actual. My region has light hilly terrain, from 50' to 1600', and moderate winds. It might do better after the tires get some miles on them, and I don't have anything in the bed so I can close the tonneau cover. It was a pleasant surprise. Note that the Rivian has a specific "Conserve" setting to get the best range. It runs only the two front motors in Conserve.
That is pretty impressive. Only downside is that 21" is a weird spec with not much availability
MXLRplus
Active Member
If somebody told me in 2000 that 20" rims would be mainstream, I'd have laughed in their face. Yes, there are more choices in 20" tires, but there are plenty of choices in 21" already. Even the Tesla Model S used 21" rims as have most major mfrs.
The Rivian 21” is a specific tire size that only pirelli makes currently. One reason why I have 22” configured. Hopefully others make a replacement 21” in that size 275/55/21.
MXLRplus
Active Member
Tirerack has incorrect data so I can't use their search engine, it claims a 275/55-21 is 27.7" dia and fits a 10-11" wide rim. It should be roughly 33" on a 9. Normally what you do search tires with the same ~dia, load and speed rating.
But yes, that specific profile currently has only a single design and mfr as of today that I can find.
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