When EPA range was given, is that with areo covers on? What about the sport wheels?

[Big-T]

I've had a question nagging me for a little bit, more just for my own personal knowledge than anything else since many posts wind up talking about range in one way or another.

SR (Standard Range) Model 3 has a rating of 220 miles
LR (Long range) Model 3 has a rating of 310 miles


First thing I'm not clear on - Do the aero caps ADD 10% range, or is the rating of 220/310 measured with the covers already on?

(If they were measured with the covers on then if you decide to take them off you'd get 198/279 for range with the 18" wheels without caps. If they were measured without the caps then you'd get 242/341 if you keep the covers on)

Second thing - what effect do the 19" have on range compared to the 18". You would assume they're not as efficient as the 18" with the aero covers on, but they look like they could be more efficient than the 18" without the covers on.

Last thing: - If there is a difference in mileage between the 18" and 19" rims - do we even know if this EPA range was tested with the 18" or 19" rims?

 

[DR61]

I don't recall there being any official statement that the aero wheel covers add 10% to the EPA combined range rating. It is highly unlikely in my opinion. It is still an open question which wheel size was used for the EPA tests of the long range M3.

Also, I don't think the official EPA range for the short range M3 has been published yet.

 

[Big-T]

Ah thank you. I didn't realize the 220 miles on the short range wasn't EPA vetted. I think the 10% increase in range came from this Electrek.co article back in August citing Tesla's VP of engineering. Maybe somewhere else, it seems to be all over the place now.

 

[gregincal]

Ah thank you. I didn't realize the 220 miles on the short range wasn't EPA vetted. I think the 10% increase in range came from this Electrek.co article back in August citing Tesla's VP of engineering. Maybe somewhere else, it seems to be all over the place now.

In my opinion that article totally misread the offhand comment of somebody chatting at a supercharger. If anything, he meant that the 18" aero wheels had a 10% range improvement over the 19" wheels, because it was in the context of choosing which wheel to buy, not about removing the caps. However, he did not specify EPA range. He could have been talking about anything (10% improvement in range when he drives 80 mph on I5, for instance). It never came from anywhere else, and is an example of really dubious internet "wisdom".

 

[insaneoctane]

We don't know which wheels Tesla used when they tested the the LR M3. Basic math indicates the standard battery M3 should have between 213 and 230 without accounting for SR's weight reduction, so the claimed 220 is reasonable and seems to match LR testing with whichever wheels they actually used. I'm interested in having Tesla ultimately tell us which wheels they used because we now know that the EPA test for the LR resulted in 334 miles of range which Tesla chose to voluntarily reduce to 310. If they used the 19" wheels, then the range could go up even more! That said, I don't think the 10% savings number has been accurately positioned. I don't think in regular driving, there is any change of the aero covers offering 10%. I suspect the ONLY way you'd ever see 10% from the aero covers is at sustained high speed (ie. > 75 MPH). I'd expect 3% to 5% is more typical for the average driver.

 

[Troy]

First thing I'm not clear on - Do the aero caps ADD 10% range, or is the rating of 220/310 measured with the covers already on?

1. The 10% claim originated from this article. The actual number might be 5% or somewhere between 5-10%. Tesla didn't say whether the EPA tests were performed with aero covers on or off but my guess is they were on because Tesla always tries to maximize the range. For example, they use the smaller wheels (1*) and turn on the range mode setting (2*) in EPA tests. Also, the EPA rules would encourage them (3*) to have the covers on because the standard configuration comes with the covers.

(1*) Source: See the footnote #2 below the first table here.
(2*) Source: Jerome Guillen from Tesla (former VP of Sales and Service) Quote: "EPA testing is with range mode “on”, given that it is assumed customers will use that function when they want to drive the farthest" Source: See #2 near the end of the message here.
(3*) Here is the relevant EPA rule:

EPA: Optional equipment that decreases aerodynamic drag and which has a projected installation rate of less than 67 percent on a carline in a test group must not be installed on the test vehicle ... Source

The EPA rules seem to be focused on preventing over reporting. They don't care about under-reporting. The rule actually doesn't say "Optional equipment that decreases aerodynamic drag and which has a projected installation rate of more than 67 percent on a carline in a test group must be installed on the test vehicle ..." Therefore this doesn't prevent Tesla from removing the covers to intentionally score a lower number. However, it makes it more likely that the covers were on.

2. The difference is only 3% based on Tesla's blog post here comparing the Model S with 19" vs 21" wheels.
However, the difference is 10-15% based on a footnote Tesla used to display on the Model X design studio comparing the 20" vs 22" wheels. Here is a screenshot:

3. Tesla uses the smaller wheels in EPA tests even for performance cars that sell mostly with the larger wheels. For example, the Model S P85 and P85+ were mostly sold with 21" wheels but the EPA tests were done with 19" wheels. See the footnote #2 below the first table here. In addition, the Model S P85D was tested with both 19" and 21" wheels and initially Tesla advertised both range numbers (see the screenshot here) but then they advertised only the higher score with the smaller wheels.

 

[thelastdeadmouse]

I'd wager that the aero wheels account for a ~10% reduction in aero drag, which in turn would mean a 5-8% increase in EPA range. Considering that they're both the standard wheel and the most efficient, I'd guess that the chances that they were not used when determining the vehicle's range are approximately 0%.

 

[shokunin]

There are multiple variables involved. The aero covers assist in reducing drag, which would come into play at higher speeds and help improve highway mileage, but may do little to help city driving.

The plus one setup from 18 to 19 is pretty small compared to the larger plus two setup from the 20 to 22" wheels the model X. The larger the rim the more mass you have that is farther out from the center axle. The farther the weight is from the center of the axle the more torque is required to rotate that mass, however, it also means potentially better regen as well to slow down that mass.

Since the areo wheels are the base, no-cost wheels, it's almost a given that they were used in testing.

The tires used in the 18 or 19 will also have an impact as one set may have less rolling resistance than the other.

Maintaining proper tire pressure is key to get good highway mileage as it affects the tire contact patch and rolling resistance.

 

[ninefiveone]

10% is highly unlikely. Off-hand comment @supercharger, etc.

3% because of lighter wheels (18"vs19") is likely, especially in city driving where accelerating the wheels happens a lot vs steady state highway cruising

2-5% because of aero covers is possible on the highway where aero makes a big difference. Makes no difference in the city.

Since the two benefits happen exclusively, they can't be added together. You can get 3% more range in city, you can get 3% more range on the highway, but you're not going to get 6% total added range.

Between the two, it would be reasonable to expect a 3-5% range hit from the 19" wheels and it would be prudent to apply that to the 310 mile range (taking it down to 295-300 mile range). It's possible, Tesla already accounted for that when they under-reported their numbers but it's safer to have conservative expectations until real facts come out.

 

[jsmay311]

I might be wrong on this, but I always thought that most of the reduction in driving efficiency with larger rims was due to increased rolling resistance associated with thinner-sidewall tires (which are often designed more for performance than efficiency) rather than from the increased weight of the rims themselves.

We don't have M3 rim weights yet, but this article from C&D which tested different rim sizes on a VW Golf and compared their specs/performance/efficiency showed that going from an 18" rim to a 19" rim only added 3 lbs per wheel+tire. So 12 lbs added total.

Granted, since the wheels+tires are a rotating mass, they require more energy to accelerate than a fixed part. If 100% of the added weight was at the very edge of the tire, you'd multiply the weight by a factor of 2 to get its total inertia, but that isn't the case here. So let's multiply that 12 lbs by a factor of 1.5 to get an estimated effective weight increase of 18 lbs*.

Adding 18 lbs of effective weight to a 3814 lb M3 LR plus a 175 lb driver only adds 0.45% to its overall weight*. That little amount of weight certainly would not account for even a 1% reduction in efficiency, let alone a 3-4% reduction.

(*I know this is an imprecise approach and conflates weight and inertia, but I think it gives a decent ballpark estimate.)

 

[jsmay311]

2-5% because of aero covers is possible on the highway where aero makes a big difference. Makes no difference in the city.

People should really stop saying aero makes zero or negligible difference in city driving. Of course that's not true. It just makes less difference than at higher speeds.

Anyway, much of people's "off highway" driving is on streets with 35-45mph speed limits where people routinely do 40-55mph. Aerodynamic drag matters plenty at those speeds.

Heck... even the very-conservative EPA "city" cycle includes stretches with speeds over 50mph.

Detailed Test Information

 

[SageBrush]

The larger the rim the more mass you have that is farther out from the center axle. The farther the weight is from the center of the axle the more torque is required to rotate that mass, however, it also means potentially better regen as well to slow down that mass.

True enough, but not really relevant to highway driving where range is most important.

 

[SageBrush]

Anyway, much of people's "off highway" driving is on streets with 35-45mph speed limits where people routinely do 40-55mph. Aerodynamic drag matters plenty at those speeds.

Easy enough to quantify "plenty."

If average Highway speed is 2x city then Highway Aero is 4x
If you expect say a 8% reduction in Aero with wheel covers at highway speeds and therefore ~ a 4% gain in range (since Aero will be about half of total losses,) the improvement in range in the city with the covers will be ~ 0.5% when Aero is about 25% of total losses

 

[omgwtfbyobbq]

Like Troy said, Tesla had to use the larger wheels/tires on the P85D's EPA testing when it was first released because more than 33% of sales from that carline, which I think was just the P85D at the time, came with those wheels. Once Tesla started offering/selling the 60D/85D with the smaller wheels in sufficient numbers, and the take rate for the 21" wheels dropped below 33% for the whole carline (60D/85D/P85D), Tesla was able to use the smaller 19" wheels for the EPA ratings on all of their AWD cars.

My guess is the 3 will be similar, especially if production is closer to the end of Tesla's 3-month delivery window than the beginning. The first cars sold will all be long range/premium package, and as long as more than 33% of those buyers purchase the Sport wheels, Tesla has to use them in their EPA tests. Once Tesla sells less than 33% of cars with the Aero wheels, which I'm guessing will be the norm in 2018, they can use those on their EPA tests.

If Tesla can somehow keep the Sport wheel purchases to less than 33% of all Model 3s sold in 2017, they can use the Aero wheels on their EPA tests, but I don't think that's likely. Using the Sport wheels may also help them anti-sell the 3 and push some customers towards the S.

 

[T34ME]

If Tesla can somehow keep the Sport wheel purchases to less than 33% of all Model 3s sold in 2017, they can use the Aero wheels on their EPA tests, but I don't think that's likely.

Referencing data from model3tracker.info with a sample of 10K reservationists, 85% are opting for the aero rims and 15% for the 19" sport wheels.

 

[omgwtfbyobbq]

Referencing data from model3tracker.info with a sample of 10K reservationists, 85% are opting for the aero rims and 15% for the 19" sport wheels.

I remember seeing that mentioned before. Was the 10k sample all current owners/line waiters who are going to buy long range/premium package cars? If so, I can see it.

If that's any of the ~500k reservations, then I doubt that's enough info to assume > 66% of the 2017 sales will be with Aero wheels.

 

[T34ME]

I remember seeing that mentioned before. Was the 10k sample all current owners/line waiters who are going to buy long range/premium package cars? If so, I can see it.

My understanding of the data is that it is reservationists of all types in general. Everyone can add their preferences if you wish. Go to the website, it is very interesting.

 

[omgwtfbyobbq]

My understanding of the data is that it is reservationists of all types in general. Everyone can add their preferences if you wish. Go to the website, it is very interesting.

In that case, I wouldn't bet on Aero wheels being on more than 66% of 3s delivered this year. It's possible, but I don't see it as likely, but we won't know for sure until we see Tesla's EPA application.

 

[FlyingKiwi]

I
First thing I'm not clear on - Do the aero caps ADD 10% range, or is the rating of 220/310 measured with the covers already on?

1) no-one outside Tesla knows how much difference the Aero covers make and at what speed. Is it 10% range, 10% Aero drag reduction, at 60mph, 80mph or????

2) we don't know whether the 310/220 mile range was with or without Aero wheels and covers..

It's all speculation based off a casual comment made by a guy at a supercharger, not worth paying attention to until somebody from Tesla releases some actual data or somebody with a model 3 with Aero wheels does some testing.

 

[melindav]

Referencing data from model3tracker.info with a sample of 10K reservationists, 85% are opting for the aero rims and 15% for the 19" sport wheels.

Those numbers are very likely skewed as most of the records were entered before the actual wheel options were added in.
If you take a look at the photos of delivered cars, they are about 50/50. This poll shows just over 50% choosing aero over the sport wheels.