Model 3 Aero Wheels Up Efficiency By 10%, Claims Tesla VP Of Engineering

AUG 23 2017 BY ERIC LOVEDAY 78

With Cover Removed

Did you know that those aero wheel covers on the Model 3 can increase efficiency by approximately 10%?

We didn’t and we’re not sure we believe that figure as it seems a bit high, but according to a Tesla Motors Club member who claims to be the vice president of engineering at Tesla, those covers are indeed capable of boosting efficiency by something close to double digits.

355rockit posted over at Tesla Motors Club that he spoke with this VP of engineering at a Supercharger station. The VP was driving a Tesla Model 3 fitted with the aro covers. When asked why he choose these wheels, the VP’s response was something along the lines of this:

“He said that he went with Aero since he wants more mileage and said the gain is ~10%.”

We don’t think a 10% bump in range in possible just by fitting covers, but we don’t have a Model 3 to test right now, so we can’t exactly prove him wrong.

Those aero wheels have been the focus of much criticism on the Model 3, but now we know they do indeed increase range and if you absolutely hate them, then you can always remove the covers like this Model 3 owner did.

Source: TMC via Electrek

Categories: Tesla

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78 Comments on "Model 3 Aero Wheels Up Efficiency By 10%, Claims Tesla VP Of Engineering"

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If that were true, those wheel covers would be standard equipment.

Huh? They are the standard wheels.

They are.

They are also very similar in design to the Bolt wheels with the plastic inserts so I assume that there is some advantage in concentrating on the wheels.

and also the original Honda insight and the EV1 both had enclosed wheel arches on the rear wheels.

The new Clarity FCX does a little bit of that as well.

But those are ugly cars unlike the Model S.

A simple question to ask is ‘percent of what?’

I would extend your comment. If those wheel covers helped that much, they’d be standard on ALL VEHICLES EVER. Surely vehicle wheels and covers matter but 10% of overall efficiency is an insanely large number

Maybe he meant to say – increased range by 10 miles instead of 10 percent. Which is still a valid reason for the aero wheels but a more believable statement.

That was my original guess on the last Wheel Cover article.

It might have moved the Cd from 0.23 to 0.24 which will result in a loss about 10 miles…

They are only effective at hi-way speeds & for the most part 10% or close to that would be believable @ hi speeds..#2)I wonder if the range was calculated with these covers on.???

10% of Aero Cd, might have been meant, so no covers might be Cd 0.23, and covers on might be 10% better, at a reduction net of 0.023, taking total Cd down to 0.21.

That might be a minimalistic improvement, but every bit belps!

Minimalistic? Double speed is quadruple energy needed. AO 10% CD improvement relates to 21% energy improvement.

I rather think it’s 10% energy improvement, so 4,8% cd improvement

” so no covers might be Cd 0.23, and covers on might be 10% better, at a reduction net of 0.023, taking total Cd down to 0.21.”

You got it wrong. The Cd is 0.23 with it on since it is standard feature.

Without it, it might have been 0.24 or higher.

Probably between 5-8%. As for not all vehicles having them is due to the way most braking systes are designed: pads can get very hot and their design deflects air to cool them down. Tesla’s and other EVs use mostly regen limiting to a minimum the use of the actual breaks and so benefit from not having a turbulent air area on each wheel well.

We need a detailed lowdown on how EPA does their fuel economy testing. When manufacturers offer multiple wheel options, how does the EPA take that into consideration when verifying fuel economy numbers? Do they just test the vehicles with standard options only?

Standard only.

Which is probably why these covers are standard.

I wonder if they added them to get the minimum range number they needed. Lots of people may take them off and get worse mileage. And they can do that if they want. Just know your range will decrease a little.

“I wonder if they added them to get the minimum range number they needed”

Yup to hit that original 215 miles goal without putting some extra battery in for cost reason.

I can’t wait to see how that base version does…

IIRC the EPA requires that any option with a significant take rate (I think it is 20% or higher) is blended into the overall figures.

(⌐■_■) Trollnonymous

Standard options.

That way when I get my car, I can replace the tires with ones with more grip, less aero with more rolling resistance so I can b1tch and moan about how I don’t ever get the EPA miles advertised.

I have to also add in my 500W Amp and dual 12 inch Sundown comp series subwoofers too.

Don’t forget, the added drag of rolling down all the windows, and using minimum regen and eratic driving styles!

I’d believe a 10% increase in the aero of the wheel itself…but not 10% of the vehicle overall…

Yeah, the aero wheel is 10% more efficient than the non-aero. That doesn’t mean the efficiency of the overall platform changes that much.

Ya, yet another selective statement coming out of Tesla. Still, 10% is 10% 😀

This.

The ability to take a phrase and make the press coverage of that phrase take it way out of context is their specialty.

Come on, it isn’t a statement frmo Tesla. It is a guy presumed to be an executive at Tesla in a very ambiguous statement. Not to be confused with a press release or marketing release from Tesla.

Thank you!

Taking an indirect quote plus taking it out of context, and then asserting Tesla “claimed” that, is pretty far from Truth.

This is more like a game of “telephone”.

Or, as we called it: “Gossip”, same game, different name!

Not surprising. The Model S aero 19″ wheels were 10% more efficient than the standard 19″ wheels. The Model 3 aero 18″ should be at least 10% better than the Sport 19″.

This is a bit in line what I was thinking.

What I presume the engineer said is that the the 19” aero wheels are 10% more efficient than the 21” Sport wheels. I’d say its not just aero caps vs non aero caps on the same wheelsize, but the 19” with aero caps vs the 21” sport. I can believe this numbers.

I have a Renault Zoe with 17” wheels. I’ve read in several places that I’m losing between 10 and 15% of range compared with the 15” wheels. It also matches my experience. In Renault Zoe’s case it’s not only the wheel size, but also the width and that the 15” and 16” wheels have special EV tires available, whereas they do not exist for the 17” version.

Well, it’s just speculation.
But, if this is on any comparison value, pro cyclist use expensive sets of wheels just to gain tiny bit of aerodynamic, and they pay a hell of cash for a few watt save on power.

When you don’t have much to spare, you count everything.

Love the look. A little like some of my favorite “monoblock” euro wheel designs.

It may well be 10% at top speed (130 mph?).

But since Horse Power attributable to wind resistance drops off as the cube of speed, that would be more like 1.25% at 65mph.

(One attaboy to whoever finds the gross flaw/oversimplification in the above reasoning)

I’m not going to get into the fine points of power required being the cube of speed vs the drag being the square of speed, because I find that whole issue confusing.

But one fallacy there is that the EPA does not, repeat not, test cars at 130 MPH! And it’s the EPA’s range rating (and, unfortunately, MPGe ratings) that concern us here.

Hmmmm! True.
Just not sure what the”VP’s” actual frame of reference was. (Up to 10% ??)

If it was my car, I’d be looking for a compromise solution. Even if those covers do decrease total drag on the car by 10%, which seems counter-intuitive* but may be true, I’d still be looking for some aftermarket wheel covers that would sacrifice a tiny bit of energy efficiency in return for covers which were not so aggressively ugly.

*But perhaps what causes drag is inherently counter-intuitive. I was reading something the other day that posed this question: If you were to drive down the highway holding a traffic cone outside the window, which way should you hold it to minimize drag? The intuitive answer, of course, is to hold it with the tip pointed forward. But according to the article, this is wrong; holding it backwards produces the lowest drag.

I would keep the covers on for long trips and off for local driving. Heck even tires can make a huge difference in efficiency. I switched to non-eco tires for the last 5k miles of my Volt lease and saw my EV miles drop at least five percent.

“aggressively ugly”

*eyeroll*

Jeez, aesthetics are subjective.

Yes, they certainly are.

Just out of curiosity, do you actually disagree with my entirely subjective opinion? 🙂

This would improve aero because rims are often designed to draw air through the brakes to cool them.

These covers will reduce brake cooling while increasing mpg, both by reducing flow through the rims.

The traffic cone thing could easily be wrong actually, it’s an expression of how a blunt front end actually works well aerodynamically and how a blunt back end creates a negative pressure zone behind the object that is continually trying to drag the object backwards.

I’m not sure a traffic cone would really work this way because it is such an extreme example. But the principle is sound. Within reason, blunt at the front and tapering at the back is the way to go.

“The intuitive answer, of course, is to hold it with the tip pointed forward. But according to the article, this is wrong; holding it backwards produces the lowest drag.”

For anyone with the most basic aero knowledge, they would have chosen the second case. But “intuitive” or “typical” answers would be often made from an uneducated or unscientific knowledge base so it isn’t surprising that it isn’t correct.

It is no different than pickup truck drivers who used to think (intuitively) it is less drag to drive with tail gate down than up when in actuality it is less drag to drive it with gate up.

Drag is all about the type of turbulence generate and after all we can always decorate those fugly covers 🙂

You should hold the cone sideways for lowest drag, instead of tip or base to the front, then the area perpendicular to the wind is minimized. 😉

Apparently your traffic cones are much shorter than ours. 😉

I don’t care what they look like. Give me efficiency! I like ’em. If a completely smooth cover were even better then give me that!

I know, I’m not typical. But I think it is good to have options like this for people that want it.

(⌐■_■) Trollnonymous

He11, if we want more efficiency why not dimple the whole car “Mythbusters style”!

I see a twizy in your future a third of the energy per km of a Tesla model S.

Looks like a solid idea to me!

Just drive a giant sized golf ball LOL

We would have done more to reduce global warming, but aesthetics must be preserved.

I hope some of the drivel we spew on the internet will somehow be preserved for our grandchildren’s amusement.

😀

Exactly.

I hate those “vague” information on Tesla.

Is it 10% on the wheel, the car or is it 10% of the range at certain speed? All of those things are different.

10% on the wheel itself is almost “NOTHING” if wheel only contributes to about 25% of the overall drag (0.25*0.9 = 0.225 or a reduction of 2.5% in overall drag). If it is overall car drag (which is more likely to make that design change), then that is a big deal which would implies more than 10% in range improvement at hwy speed but far less at inner city speed.

If it is overall range reduction, then what is the speed at which range is about 10% lower?

“If” it is total range reduction, then for the 220 miles base version, it would have been just below the 200 miles range mark (198 miles) if it is 10% range reduction!

I wish it would have been more clear on what that 10% mean…

Come on, it isn’t a statement from Tesla. It is a guy presumed to be an executive at Tesla in a very ambiguous statement. Not to be confused with a press release or marketing release from Tesla.

I agree. That is what my next post said.

But if “we assume” that it is somewhat true, then I would like to know which area (out of the 3 that I listed) are the 10% applying to.

““He said that he went with Aero since he wants more mileage and said the gain is ~10%.””

That sounds like a total range change of 10%.

But take it with a big grain of salt since this is reported by some guy on a forum in talking with some guy who claims to be VP of engineering at some random charging site with “off record” discussion…

(⌐■_■) Trollnonymous

“take it with a big grain of salt since this is reported by some guy on a forum in talking with some guy who claims to be VP of engineering at some random charging site with “off record” discussion…”

+100

True.

But if we assume the comments are correctly reported, I’d guess he’s talking about 10% better range at highway speeds, i.e. 70 mph or similar.

My guess is 10% gain in range from wheel cover and narrower 18″ tire vs 19″ package at a steady 70 mph.

Maybe 1% gain in city traffic.

Yep. Agree this sounds reasonable.

Silly season is upon us!

It’s what happens in between the 30 Model 3s out the door to employees and real production ramp up when actual cars get out to publications and reviewers to analyze with a fine-toothed comb.

“This guy met this guy who said he was this guy and he said that this guy said…”

I’m glad InsideEVs says this story is unsubstantiated. Otherwise they’d be down to the level of CNN or the Washington Post!

L 🙂 L

“Silly season is upon us!”

and what amazes me is how many comments there can be about nothing.

So I’m going to improve range by 10%???

You have to be kidding me.

Even on a big semi all the aero losses total combined are only around 15% of all the losses.

http://insideevs.com/tesla-semi-truck-battery-is-how-big/

These wheel covers are as good as elimating almost all the aero losses.?

I think it’s more like 10% of 10%.=1%

“Even on a big semi all the aero losses total combined are only around 15% of all the losses.”

What? are you serious? Aero loss is ONLY 15% of all losses combined?

What planet do you live on? The one with little to no air?

Typical vehicles with 0.3 Cd would have lost half its power at 60mph. Half of the power cruising at 60mph goes to the counter the aero drag alone!!!!

15%? LOL. Where did you get that number from?

You must be confusing the difference between the efficiency of a typical electric driven train (which can be 85% efficient) to what aero drag is.

I guess Spark EV is right, I am having PMS like problem because there are too many stupidity out there…

georgeS said:

“Even on a big semi all the aero losses total combined are only around 15% of all the losses.”

Sorry, George, but you have misunderstood what you’ve read.

At 55 MPH, the typical family car spends about half its power fighting air resistance. Half, as in 50%. And it rapidly gets even worse at higher speeds, altho of course less at lower speeds.

I’m not sure what the fraction of loss due to drag is for a semi tractor-trailer, since it’s longer in relation to its frontal area. What I have read recently is that by adding “skirts” and a removable “boat tail” to a typical semi trailer, you can improve energy efficiency by ~15% at highway speed.

My understanding is that radically streamlined semi tractors can reduce drag even more than that.

Speaking of radically streamlined:

https://i.pinimg.com/736x/6a/39/eb/6a39ebe06fd5f44c1b5a95868a0d4cd3–recreational-vehicles-automobile.jpg

I think I understand GeorgeS’s confusion now.

That diagram he is referring to is based on total energy input at the tank.

So, in that case, “majority” of the energy lost is at the engine where much of it are turned into heat.

Once that energy is converted to motion, then it is split between Aero and Tire which confirms by that diagram in terms of the % loss due to the two area.

Of course, that is completely different from “loss” in the sense that drag and tire loss are “pure” loss which means that even if the powertrain is 100% efficient and no aux loss.

Aero and tire loss are independent of “all other system losses” regardless of the type of powertrain.

But quoting 15% is truly misleading for sure.

Well said, MMF.

And much more reasonable than your first “another PMS attack from MMF” reaction, accusing him of “stupidity” just because he didn’t know something you do.

Guess what? He knows things you don’t know, too. Does that make you stupid?

Two things I’ve noticed about these wheels. One, they’re non-directional. Most manufacturers, even ones who make expensive cars, cheat on wheel designs. They LOOK really aerodynamic yet they only make the one wheel, not two – one for each side. Thusly, all those sloped and winglike adges are reversed on the other side of the car, now pushing the wind, not slicing through it. GM’s Volt designers crowed that the first gen Volt’s wheels were designed to pull turbulent air out from underneath the car. Sure sounds good on paper until you saw that the wheels were the same, not directional. Might work on one side of the car but the blunt, flat sides spun forward on the other. These wheels don’t need a Left version and Right version to be aero. The design of the spokes LOOKS directional, but both sides of each blade are aero facing the oncoming air. Second thing I noticed is that they’re all grey, but the detail part of each blade could be silver to the hub and that would be far more attractive to my eye. Two-tone rather than all grey. They aren’t bad though. Curb rash will be a problem as one… Read more »

James,
They are curb rash protectors from the looks of them.

Just think, you can make your new Model 3 go farther, you can eliminate curb rash

….and make your new Model 3 look like sh!t.

LOL hard to resist

If this engineer simply claimed 10% without stating the conditions, then he is one ignorant engineer when it come to aero
forces. That wheel around town at speeds , say, below 35 MPH will have almost no effect.
Aero drag is an exponential force, you know, not linear. Tesla must be hiring college drop outs these days.

It does say “VP” part… =)

once some “engineers” become managers or executives, they seem to lose all their technical knowledge. =)

Is there any company willing to convert Model 3 into a spacious wagon where the windshield will be in 90 degree angle.
Wagons are becoming popular.

It will be better if they can convert it into a 6 seater: Seating 3 passengers in front seat as well. Its 73″ width is same as Chevy Impala which had 6 seater feature in earlier models.

Buy a Bolt at a huge discount or an eGolf…For Teala, it’s the Model Y or whatever they name it…Otherwise you’re paying a custom fabricator the big bucks to create a wagon…

These wheels will be nixed once the EPA rating is in. They are just that ugly. The Bolt has nothing on these turds.

Bring back the Hubcaps!

“choose these wheels, the VP’s response”

Note “wheels” not “wheel covers”…The best way to interpret this is the 18″s with covers and the included tires are a 10% improvement over the optional 19″…Downsizing to lighter weight wheels is a common practice of hypermilers and there are multiple threads where the Gen3 Prius many downsized from the higher trim alloy 17s to the steel 15” and reported MPG improvements

When I see nice clean round numbers (like 10%) from unofficial sources, I automatically assume there is some guesstimating and/or rounding going on.

The wheels and the wheel openings contribute about 20-30% of the aero drag. Remember that the top of the wheels are moving forward at TWICE the speed of the car, by definition.

And turbulence at the wheels screws up the air flow rather back.

MOST of the aero drag comes from the back of the car.

Doing an approximate calculation using the EcoModder online calculator ( http://ecomodder.com/forum/tool-aero-rolling-resistance.php )

The Model 3 hits 50% of the load on the drivetrain between 45 and 50 MPH.

So, 10% of the range at hwy speed is totally possible with wheel cover which is standard. without it, it may lose easily 10% of the range at hwy speed.

Whatever

Someone with Aero wheels can be smashing the pedal and getting less range while someone with 19’s will be driving conservatively and achieving more range.

“10%” my ass

All depends on how you drive and thats it.