As far as I know, the vehicle manufacturer picks the car, does the test, and reports the results to the EPA. An EPA audit test could either be a car supplied by the manufacturer or one purchased (but I'd guess that most of the time it is supplied).
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Porsche Taycan EPA range
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AlanSubie4Life
Efficiency Obsessed Member
I'm sure Porsche will be happy to provide the details on the AMCI methodology.
Do they multiply the results by a 0.7 fudge factor, like they do with the drive cycle results from the EPA tests? I mean, the Model 3 RWD can do 600 miles if you drive it right!
The EPA test actually goes up to 80mph.
The EPA and WLTP cycles are not different enough to explain such a large discrepancy. Tesla ratings are much closer between the two.
The EPA test lab up the street from me in Ann Arbor, MI disagrees.
You may be thinking of FMVSS requirements which are all self certified, EPA number are from the EPA only.
Basic Information on Fuel Economy Labeling | US EPA
AlanSubie4Life
Efficiency Obsessed Member
"EPA is responsible for providing the fuel economy data that is used on the fuel economy label (or window sticker) on all new cars and light trucks. The data is also used by:"
This does not imply that the EPA does the test though. For example, this document is pretty clearly from Tesla...and is asking EPA to issue the numbers, which are supported by the test results (which was obviously not done by the EPA - it was done at the Tesla Fremont facility):
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46075&flag=1
Furthermore:
Technical Capabilities of the National Vehicle and Fuel Emissions Laboratory (NVFEL) | US EPA
"NVFEL works with test laboratories used by industry to meet EPA’s standards through cooperative inter-lab correlation programs."
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Eno Deb
Active Member
That's no different in Europe. For example, in Germany the Kraftfahrt-Bundesamt does similar auditing on WLTP conformity.
Eno Deb
Active Member
Here's a description from the EPA web site:
"Fuel economy is measured under controlled conditions in a laboratory using a series of tests specified by federal law. Manufacturers test their own vehicles—usually pre-production prototypes—and report the results to EPA. EPA reviews the results and confirms about 15%–20% of them through their own tests at the National Vehicles and Fuel Emissions Laboratory."
axhoaxho
Member
I am so spoiled by the 373 miles range on my Model S Long Range.... not sure I can comfortably go back to 201 miles range on a Porsche Taycan Turbo, especially it almost doubles the price with options.
AlanSubie4Life
Efficiency Obsessed Member
EDIT: Disregard this...the WLTP numbers are really confusing...depends on configuration...
Ok, I did some digging, and there does appear to be some misinformation out there (from Jalopnik...who would have thought...). I really can't find the WLTP ratings with a simple search, though I am sure they are out there somewhere. EDIT: The links are provided below for the Turbo and Turbo S. Anyway, this is what I found on WLTP, second-hand:
'Although no combined range rating was provided, for the “Turbo” variant, the WLTP highway range rating is 237 miles (381 km) and WLTP city rating is 280 miles (450 km). The more powerful “Turbo S” receives a WLTP highway rating of 241 miles (388 km) and 256 miles (412 km) WLTP city. Given the WLTP combined rating is usually weighted 52% city and 48% highway, this should give 259 miles (417 km) for the “Turbo” and 249 miles (400 km) for the “Turbo S.” '
That's from cleantechnica, but it looks like their primary source is this page, where you can download PDFs of the individual trims:
World premiere of the Porsche Taycan: Sports car, sustainably redesigned
So, the Turbo probably has 259 miles WLTP range (not sure where this 280 number is coming from - presumably Jalopnik didn't just look at the city number...right?)
The Turbo S is likely around 249 miles. So I would expect it to end up below 193 miles EPA (I think city weighting is 60% for EPA), something like 250/263* 201mi = 191 miles.
Note how much worse the Turbo S is in the city...presumably due to sticky tires. Oddly it is better on the highway, perhaps due to the bigger front inverter.
In any case, for the Turbo, this would mean the ratio is 259/201 = 1.29 which isn't as far off as 1.4 or whatever when you use 280. Still somewhat of an outlier, but only 2 standard deviations out.
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Eno Deb
Active Member
No, the combined WLTP range ("Reichweite kombiniert") is actually up to 450 km (depending on wheel size etc.), which is about 280 miles. This is from Porsche's german site (can't provide a direct link because they use some fancy animation/scripting on their web page, but you can find it under https://www.porsche.com/germany/models/taycan/taycan-models/). The low-end range (380 km) is about 240 miles though, so that would be a bit closer.
AlanSubie4Life
Efficiency Obsessed Member
Alright, I give up. It doesn't really matter I suppose, the efficiency is just really bad. There's no way to go from the worst case number to the best case number there and derive anything meaningful as far as correlation factor goes, because we don't know what article was tested for the EPA test. Which of the wheel sizes was tested? What's the highway result (WLTP)? What's the city result (WLTP)?
I guess they aren't separate for WLTP, now that I think about it?
Anyway, like I said, I give up. There's no way to get a correlation if there's not a single WLTP number.
Eno Deb
Active Member
Wondering about that too. Is it regulated by the EPA which specific options like wheels etc. the test vehicle has equipped? It always irked me a bit that the Model 3 Performance used to have the same rated EPA range as the AWD model, even though the version with the 20" wheel didn't even come close to that ...
AlanSubie4Life
Efficiency Obsessed Member
It's allowed if the take rate is low enough. Tesla has gone honest on that now, which is awesome.
In any case it looks like the Turbo S could have a range of about 184 miles with these new numbers:
Porsche said:
412/450*201mi = 184 miles for the Turbo S...
Obviously just approximate since how the numbers change city and highway matters a lot.
But, maybe they picked the minimum range Turbo model for the test. Which would give a different number. But apples to apples, it could be 184 miles.
I guess the 4 numbers are: Turbo: 381km (min) 450km (max) Turbo S: 388km (min) 412km (max).
So assuming they just ripped off the bandaid and used the 381km configuration for the Turbo for EPA:
Best Turbo S result would be ~217 miles. (But that would not be apples to apples in some way - the Turbo S would have to be equipped with aero wheels or something.)
But do we think they used the worst Turbo configuration for this? I guess that would sort of be in keeping with how Porsche does things. That would make the WLTP/EPA ratio 1.18 which would be totally reasonable.
Maybe they sent the worst configuration results to EPA, and then used the best configuration to give to AMCI for their testing (but the number obviously still cannot be compared to the EPA result).
Probably the most reasonable explanation is that they used the least efficient Turbo configuration for EPA testing. Otherwise, it would imply that the Turbo/Turbo S could be as low as 170/173 miles (381/450*201mi, 388/450*201mi), when configured with the worst efficiency options, which seems improbable.
So most likely the Turbo S has ~204 miles range in its least efficient configuration, and ~217 miles in its most efficient configuration.
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They literally paid a company to come up with a drive cycle that makes their piss poor range look better.
There’s no excuses, this $200k car gets range about as good as a $35k Standard Range Model 3 (the few that are around).
There’s no excuses, this $200k car gets range about as good as a $35k Standard Range Model 3 (the few that are around).
This is the most believable explanation I've seen so far. The reason they'd use their least efficient version is probably because either the EPA or a lawyer told them to do so, unless they wanted to test every variant.
Daniel in SD
(supervised)
Most of that makes no sense.
The Taycan is using (approximately) an average of 15kW of power during the EPA test. What component could possibly be a significant fraction of that other than the drivetrain?
If your drivetrain is inefficient (pack power vs. motor power) that makes it more difficult to get repeatable performance as it means you're generating more heat that you have to get rid of. Conservation of energy: Motor power = pack power + heat power.
Every plot I've seen of electric drivetrain efficiency shows that the efficiency is best at maximum power.
AlanSubie4Life
Efficiency Obsessed Member
I don't know the exact weighted average speed in the EPA test, but I hand-calculated above that the static draw to explain the discrepancy (if that were the only difference - which of course it is not) would have to be 3.5kW (assuming something like 30mph average speed for the test). That's far too high to be the cause, no matter how bad the components.
The drivetrain is apparently just crap, though I still do wonder what happens to that ~3.5kW. Honestly it is all fairly mysterious. I guess there's several thousand pounds of heat sink to radiate all that heat to atmosphere - or to the cabin. Maybe they wanted to make it like an ICE vehicle and it requires minimal additional energy to heat the cabin in winter!
Now that sounds like German engineering.
lencap
Member
Like many others I'm a bit shocked by the EPA estimated range. Trying to determine the shortfall between the EPA and WLTP isn't my expertise, but I found this posting on The Verge which may explain part of the difference: (Bolding text is my emphasis, not The Verge).
Porsche was never really going to match, let alone beat, the bountiful range that Tesla offers in its vehicles, especially with the company’s first electric car. The German automaker even made explicit choices with the car that prohibit the Taycan from getting more out of its battery pack, like having the car coast when the driver lifts off the throttle instead of automatically spinning the electric motors backward to recover energy. This technique, known as regenerative braking, is something other automakers use to varying degrees in their electric cars to help make sure there’s enough battery to get a driver where they want to go. And while there is an option to turn on regenerative braking in the Taycan, it’s still not nearly as aggressive as in some other EVs.
Porsche was never really going to match, let alone beat, the bountiful range that Tesla offers in its vehicles, especially with the company’s first electric car. The German automaker even made explicit choices with the car that prohibit the Taycan from getting more out of its battery pack, like having the car coast when the driver lifts off the throttle instead of automatically spinning the electric motors backward to recover energy. This technique, known as regenerative braking, is something other automakers use to varying degrees in their electric cars to help make sure there’s enough battery to get a driver where they want to go. And while there is an option to turn on regenerative braking in the Taycan, it’s still not nearly as aggressive as in some other EVs.
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