Aero Efficiency

[stuckintraffic]

Using Aero hubcaps (18" wheels) were over 4% more efficient for me in my first test run vs Non-Aero. Anyone test on their end as well? Anyone have 19" wheels to test against?

I didn't have any cool equipment or facility to test with - i just attempted to repeat a route with and without aero and attempted to reduce some variates (e.g. used autopilot to reduce steering anomalies when possible, reduce lane changes as much as possible, etc.). I need to do more tests but figured this is a baseline to start from.

Video of my results:

 

[Yuri_G]

Looked like your Wh/mile steadily went up over the duration of the test. Assuming you were climbing in elevation, you may find a greater difference in efficiency over a flatter route.

 

[Troy]

Thanks for the video. That's the first test I have seen. Your consumption was 270 Wh/mi with 18" aero covers on and 282 Wh/mi with 18" wheels aero covers off. That means without the covers, it was (282-270)/270= 4.4% higher.

 

[Zoomit]

Looked like your Wh/mile steadily went up over the duration of the test. Assuming you were climbing in elevation, you may find a greater difference in efficiency over a flatter route.

Shouldn't matter for this relatively flat route. Both tests were the same course and conditions. Looks like he controlled for all the big variables so I believe the results.

However the implication that it should be 10% in the lead-in was based on the difference between the 18" and 19" wheel options, not 18" with/without aero covers.

 

[EV-lutioin]

Interesting, your numbers are a bit higher than I have seen from others. Several M3 owners reported consumption between 240-250 kWh with aero covers on.

 

[EfficientWatts]

Interesting, your numbers are a bit higher than I have seen from others. Several M3 owners reported consumption between 240-250 kWh with aero covers on.

Probably because of the elevation climb as another poster pointed out.

 

[Zoomit]

Interesting, your numbers are a bit higher than I have seen from others. Several M3 owners reported consumption between 240-250 kWh with aero covers on.

Good point, I would have "guessed" 248Wh/mi at that elevation and temperature going 70mph. A consumption of 270Wh/mi implies an extra 1.5kW of power being used over the drive. Looks like the test was done around 4am. If the aero test was the first one, I wonder if the car used extra power to heat the battery if it was cold soaked overnight.

Probably because of the elevation climb as another poster pointed out.

The elevation gain was only 60', from 480' to 540', according to Google Earth, which is in the noise and not a factor.

 

[T34ME]

VERY helpful. Yeah, Tesla's engineer was comparing 18" wheels with aero covers to 19" Sportwheels to get to 10%. I think your results are in the ball park - ~5% gain with aero covers compared to without covers and 5% gain with 18" wheels without covers compared to 19" Sportwheels - on the freeway. Your Wh/mi is a bit high but I would attribute that to 70mph and the temperature of 54F. I think I can get ~225 Wh/mi with 18" Aeros at 70F at 65mph.

 

[Zoomit]

Your Wh/mi is a bit high but I would attribute that to 70mph and the temperature of 54F. I think I can get ~225 Wh/mi with 18" Aeros at 70F at 65mph.

I don't think the discrepancy is attributable to just a higher speed and lower temperature. If I run the numbers, I estimate 223 Wh/mi at 70F & 65mph and 248 Wh/mi at 54F & 70mph. The former matches your experience but the latter is 8% lower than the 270 Wh/mi seen in the test.

 

[FloridaJohn]

I would like to see three Model 3 owners do this test together. One with the Aero hubcaps on, one with them off, and one with the 19" wheels.

They could all start at a Supercharger and charge up to the same level. Then drive together (but not in a tight bunch) at the same speed to another Supercharger. Record energy used and charge back up to the previous level. Then reverse the route and charge up again at the original Supercharger.

This would take into account weather conditions as well as wind effects, since all three cars would be experiencing the same conditions at the same time. That would give us a pretty clear indication of the affect of the aero hubcaps on the range/efficiency.

 

[stuckintraffic]

Thanks for the comments! I knew you guys would come up with more intelligent theories/explanations than I ever could. I would love to see the same test conditions done with 19" wheels and see how much more efficient it is compared to the two and if we can get close to that 10% difference. I'm seeking out other owners right now to try to set this up.

 

[ölbrenner]

@stuckintraffic - Thanks so much for this! Your numbers seem to fall in line with most of the consumption numbers we have been seeing. Kudos.

Even though we have real world numbers coming in, I can't understand why so many in the forums still speculate and estimate what the consumption will be (and usually on the low side).

 

[BMWLover]

Thanks for the vid, definitely was a question a lot of people really wanted tested I think!

 

[ikjadoon]

Excellent testing. 4% is solid, still.

If you're ever interested in another test, I wonder if the charge indicator is linear at different SoC? That is, is the drain from 90% to 80% the same as 70% to 60%? I remember once reading that at higher SoCs, the drain is faster? Though, as @Zoomit mentioned, maybe that's because high SoC often means "hasn't been driven in a while, so the battery is cold"?

 

[Nosken]

Speed will of course determine power used, but in my uneducated mind I would think speed would have less effect on range considering just wheel choice and not the entire car.
This could be tested by having a Model 3 run at 60 and at 70 with Aeros on, then the same test with Aeros off.
If I had a 3, I would test it.
I have disliked the photos of the Aeros, but in person they look much better. I really like the wheel under the Aero cover, both in photos and in person. If the bolt pattern and size was compatible, I would use use them on my Model S.

 

[T34ME]

Even though we have real world numbers coming in, I can't understand why so many in the forums still speculate and estimate what the consumption will be (and usually on the low side).

Because the OP's tested numbers, Kw/mi, appear to be somewhat on the high side compared to other reported numbers. Could be an outlier. It's a great test and I am grateful, but not necessarily definitive.

 

[Zoomit]

Also because real-world data has a litany of variables that most people don’t consider. For example, many people don’t think about how much even a slight breeze will have on energy consumption. So the reality is that we, the public, will be fine tuning our expectations for many years to come. In fact, it’s really a never ending process since the car will continue to evolve as well.

 

[jsmay311]

Here was my suggestion for a more exhaustive test for comparing wheels that could better account for all the misc. variables that posted I previously over at Model3OwnersClub (this was specifically for comparing 18" aeros to 19"s, but could work for even easier for aero vs non-aero 18"s):

"Two M3 owners -- one with 18" aeros and one with 19"s -- meet at a Supercharger location on a day that it's known not to be busy. Both cars charge to 100% (or 90% or whatever) and note the displayed ranges. Then both go driving on a predetermined highway route -- the longer the better -- that ends back at the original Supercharger location. Both cars drive at identical speeds, climate controls off, no drafting (keep a generous distance with any cars in front), and tires at recommended pressures.

At the end of the drive, compare the Wh/mi and displayed miles remaining.. Then recharge back to X% and compare kWh's consumed from each Supercharger (assuming this is displayed). (If possible, both use a stall that is not paired so charging rates are similar.)

And then... to go one step further and make sure any subtle differences between the 2 cars/drivers are accounted for, swap wheels between the 2 vehicles and repeat the whole process."​

 

[Polly Wog]

@Zoomit makes a very valid point regarding "a litany of variables". I increased the tire pressure on my S from 45 psi to 50 psi, and my efficiency improved 5%. I would request that the tire pressure be checked prior to another data gathering attempt, especially if multiple cars are involved.

 

[stuckintraffic]

Excellent testing. 4% is solid, still.

If you're ever interested in another test, I wonder if the charge indicator is linear at different SoC? That is, is the drain from 90% to 80% the same as 70% to 60%? I remember once reading that at higher SoCs, the drain is faster? Though, as @Zoomit mentioned, maybe that's because high SoC often means "hasn't been driven in a while, so the battery is cold"?

That is a very interesting thought in terms of additional variables to think through and will see what I can do in future tests. Thanks for the input!

Because the OP's tested numbers, Kw/mi, appear to be somewhat on the high side compared to other reported numbers. Could be an outlier. It's a great test and I am grateful, but not necessarily definitive.

Agreed that more tests need to be conducted for sure. FWIW my avg Wh/mi during my daily commute, which includes heavy stop and go traffic, is around 226 Wh/mi with avg MPH of 40ish (pure guess).

@jsmay311 I think that's a fantastic test plan. I've been posting around to see if any 19" wheel owners want to try a test but like you mentioned, even testing against another car with 18" wheels would work.

@Polly Wog - argh I should've recorded the tire pressure at times of test. Next time. Thanks for the input.