EPA Test Car Database plot

bwilson4web

bwilson4web

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I combined the 2021 and 2022 data for electric vehicles: https://www.epa.gov/compliance-and-fuel-economy-data/data-cars-used-testing-fuel-economy

So I plotted the MPGe vs test vehicle weight to get this chart:
upload_2021-8-27_21-14-42.webp

I dropped any below 60 MPGe since such inefficient vehicles might as well drive around with their brakes on.

There appears to be a sweet spot between 3750-4250 lbs (1705-1932 kg). Above this weight, the efficiency takes a dive. Below that weight, the vehicle size probably has aerodynamic problems leading to less efficiency.

Bob Wilson

ps. I'll try to attach the spreadsheet embedded in a zip file.
 

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I made a fresh chart using the same spreadsheet using one of two test protocols and plotting both MPGe and "Tesla" MPGe:
upload_2021-8-28_5-26-49.webp

Tesla engineering is focused on vehicle and drivetrain efficiency. The other EV makers with legacy design rules, not so much. My suspicion is they outsourced the drivetrain technology but it could also be legacy design rules.

Tesla engineering has a moat, absence of ICE legacy.

Bob Wilson
 
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Tesla is very, very good at designing to the test and is able to publish better numbers accordingly.
Opening up more of the battery and then telling people not to use it is one example.

Don;t get me wrong, they make some of the most efficient vehicles out there, but looking only at the EPA numbers gives a bit of a distorted view.
 
bwilson4web said:
One that is and has been backed up by fines:
https://www.epa.gov/enforcement/basic-information-enforcement

In contrast, less rigorous reviewers are using a loaned, press car perhaps from their advertisers. There is a temptation to omit unpleasant observations because it risks future press cars.

Bob Wilson
Click to expand...
Like I said, Tesla is very, very good at producing vehicles that do well on the EPA test cycles.
This makes it harder for the average owner to achieve those results in real world situations that don;t mach the EPA test cycles/conditions.
Tesla is not falsifying test info, they instead use that as their design goal.

And you are implying a journalist may have more motivation to espouse the virtues of a particular vehicle than the manufacturer?
 
DucRider said:
Tesla is very, very good at producing vehicles that do well on the EPA test cycles.
Click to expand...
It is a level playing field and if others choose a different path, too bad. But after a decade of Prius ownership and EPA roll down analysis, one lesson learned is 63-64 mph, constant speed, start-end constant altitude, on a standard day will give EPA metrics. So my testing is done between midnight and dawn when temperatures are constant and the wind minimum. If a circular route of 10 miles is available, one round works. If not, average opposite runs of 10 miles on the same route.

Now Car and Driver did a credible analysis:
https://www.caranddriver.com/featur...-factor-tesla-uses-for-big-epa-range-numbers/

The Secret Adjustment Factor Tesla Uses to Get Its Big EPA Range Numbers

How Tesla puts distance between itself and the competition while still playing by the EPA's rules.
AUG 30, 2020​

Not such a secret that apparently the other manufactures choose to ignore. Tesla has been accused of 'sandbagging' by reporting metrics that give a worse performance. You can't report an optimistic number without risking an EPA fine.

DucRider said:
And you are implying a journalist may have more motivation to espouse the virtues of a particular vehicle than the manufacturer?
Click to expand...
Here is a report of that being done:

Compared to the EPA metrics, reviewer are a mixed bag. But there are some reviewers I trust more than others. For example, the '70 mph' range tests when I've found 63-64 mph is the EPA matching speed.

Bob Wilson
 
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I think we're saying the same thing. Tesla makes maximizing the EPA results a priority.

Where we differ is on how well that correlates to owners results after purchase.

Yes, you can drive in a very specific way to achieve the EPA numbers. With some vehicles you just have to work harder to do it. Tesla is at or near the top of that list.

I'm not saying that Tesla is doing anything wrong. They didn't write the rules and they indeed are following them very, very well. I've never quite figured out when/why the EPA stopped requiring a company that tells you not to charge to 100% (except on rare occasions) to derate the range rating accordingly (as per the original LEAF). Once again, Tesla is not gaming the system, they are doing everything they within the rules to maximize the range number they can publish, and that usually doesn't result in more "real world" range.

What flavor was the Kool-Aid that came with yours?
 
I have the advantage of over a decade of Prius, Prius tuning, and EPA methodology, 2005-2019. If the other EV makers are sandbagging their EPA metrics, the fault is theirs, not Tesla.

Bob Wilson
 
Thanks for the charts Bob.

In regards to Teslas range vs real world, those who comment must realize Tesla has range below zero on the counter. Any comparison worth citing must be from full to the point the vehicle no longer moves.
 
I am working on an Open Office spreadsheet that plots the 'drag power' as a function of speed and the three roll-down coefficients. Here is an early example:
upload_2021-8-29_2-50-39.webp

I'm open to suggestions. My plan is to use the secondary axis for Standard Units, kph and kW. Reduce top speed to either 100 or 120 mph. Offer a two car or four car comparison charts. Add minor grid lines between the major. Add the EPA reference velocity, 63 mph, for highway MPGe. Hopefully, we'll get some good technical suggestions.

When it looks good, I'll share the Open Office spreadsheet in a ZIP file.

Bob Wilson
 
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