InsideEVs Podcast episodes

This is a deep dive into EPA mileage and range versus user 70 mph benchmarks. One problem being EV makers can use either a two or five test metric where the two test method gets an 'engineering factor' adjustment. But all vehicles have a set of 'roll down' coefficients that map to the drag force and subsequent power needed to sustain a given velocity. For example:

upload_2022-1-28_6-53-21.webp

  • 63 mph - earlier Prius benchmarks derived the EPA mileage
  • The four vehicle, drag power at:
    • 63 mph (EPA) and 70 mph (user) percentage (EPA/user)
    • 15.0 hp 19.0 hp 79.2% - Lucid Touring
    • 16.7 hp 21.2 hp 78.6% - Model 3 LR AWD
    • 17.2 hp 22.0 hp 78.0% - i4 eDrive
    • 18.2 hp 22.7 hp 79.9% - Model S Plaid
  • Many truck companies limit highway speed to 65 mph
    • following, not tailgating, minimizes your being tailgated
    • some risk of rock and slush impacting vehicle
    • very efficient cross country practice using dynamic cruise control
The EPA listed MPGe can be either a two or five test average which introduces an unnecessary variation. I would prefer to see the five test as the standard because it includes weather extremes. Regardless, the roll down coefficients can calculate the 'drag power' needed at +20 mph speeds. Notice the 70 mph metrics will be about 79% of the five test, EPA listed metrics.

Bob Wilson

ps. A single tank, 2010 Prius benchmark from 2013:
1000mi_721a.webp
 
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About today’s podcast:
  • At age 72, Autopilot and the urban version, FSD, extend my ability to drive safely. Calculate and imagine when you also will be too old to drive without FSD level automation. For fun, imagine feeling a heart anomaly, telling the car to drive me to the ER and arriving in time to be resuscitated.
  • Does Tesla have to lose money for you to believe in their Mission Statement? Get real and examine your own goals and objectives for the earth inherited by your offspring. Snark about Tesla profits is so Elizabeth Warren.
Otherwise, an excellent podcast.

Bob Wilson
 
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bwilson4web said:
Here is an example chart:
View attachment 15045
  • Lucid has excellent low drag at low and high speeds
  • Model 3 has higher drag at lower speeds - tires
  • Model 3 has better drag than Plaid at high speeds
Based on this chart, I would look at lighter weight and narrower tires for the Model 3. Better tires would make the Model 3 more efficient in kWh per mile.

I've embedded the OpenOffice spreadsheet in an attached ZIP file. If you have questions, let me know and we can tweak the chart for other vehicles and details. For example, I would set the X-axis scale to 60-70 mph and the Y-axis scale to expand the HP details. Prius experience has shown EPA metrics can be achieved by holding 63 mph on a benchmark loop.

Bob Wilson
Click to expand...
This is pretty cool, Bob. Thanks for sharing - I shared with the editorial team as well.
I'm would be curious to see the Kia EV6 and Hyundai Ioniq 5 compared, along with maybe the Tesla Model Y. We're going to do a 70-mph range test with Ioniq 5 soon, and judging from posts I see about it in various groups, I suspect its aero Cd really affects it at higher speeds.
 
upload_2022-1-30_1-10-56.webp

Drag power at 70 mph:
  • 30.1 hp - Ioniq5
  • 21.2 hp - Model 3 LR
  • 23.6 hp - Model Y
  • 28.5 hp - EV6
GOOD LUCK!

Bob Wilson
 
bwilson4web said:
View attachment 15079
Drag power at 70 mph:
  • 30.1 hp - Ioniq5
  • 21.2 hp - Model 3 LR
  • 23.6 hp - Model Y
  • 28.5 hp - EV6
GOOD LUCK!

Bob Wilson
Click to expand...
That's amazing and, I think, a pretty informative snapshot.
Kyle just did a 70-mph test on Ioniq 5 AWD, and as you can imagine by looking at your graph, the results weren't great. (I don't think he's released the number yet, but we'll talk about it on the Podcast this Friday.)
 
FYI, I can modify the graphs to show kWh/mi (or kWh/km) as a function of speed. By hand, one HP is 746 W.

For my Model 3, I've plotted range as a function of speed using the battery kWh. I needed this when dealing with the earlier, less dense SuperCharger network. Addition of two SuperChargers in Arkansas and relocation of the Joplin SuperChargers has made trips to Coffeyville KS trivial.

Bob Wilson
 
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Domenick said:
So, the Ioniq 5, then, would take (30 X 746 Wh) 22.38 kW to travel at 70 mph?
Click to expand...
Correct:
  • in one hour, 22.38 kWh
  • 320 Wh/mi ~= 22.38 kWh / 70 mi
  • 3.13 mi/kWh ~= 70 mi / 22.38 kWh
This is the drag power and does not include battery, inverter, and motor losses. The ratio between this and the benchmark gives a first approximation of the drivetrain efficiency.

Bob Wilson
 
I logged into the live show in case there were questions about the EPA roll-down coefficients. I did see where Tom and Kyle discussed differences that sound like "density altitude." A combination of altitude, temperature, and barometric pressure, you two could calculate the density altitude and use it as a scaling factor to normalize your respective 70 mph benchmarks.

As for the Umlaut table, the "Price Transparency / Payment" for 10, SuperCharger, compared to the others is so wrong as to be laughable. At that point, I lost interest because a blatant error often means there are likely to be others.

GOOD LUCK!

Bob Wilson
 
About #99, the short news and Biden saying’Tesla’ were done well. Having owned a 2017 Prius Prime and still a 2014 BMW i3 REx, some lessons learned:
  • Must have pure EV mode for 72 miles. No below 55 F laws that force the ICE to run.
  • Highway efficiency is not as important as gas mode range that should be +150 miles. Optimize urban drives.
  • A derated engine must have Atkinson valves and recirculated exhaust. Also the engine coolant loop should provide optional cabin and battery heat.
  • Must have a fast DC charging rate closer to peak battery rate, the 50 kW limit and no Prime fast DC charging were stupid.
  • NO traditional automatic transmission. Prime gets a pass because of the one-way clutch allows MG1 and MG2 to work as one.
Flogging with a wet noodle, your discussion of IONIQ 5 testing at 70 mph reminds me of the old Prius vs EPA discussions. The plural of Standard means no Standards at all.

I still enjoy your podcasts.

Bob Wilson
 
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