Hey all,
So after a wait that we're (mostly) all familiar with, I picked up my S with 19" wheels on Friday. Before picking it up, based on photos I'd seen online, I was sort of waffling on hubcaps vs no hubcaps vs different wheels; the hubcaps looked OK in photos, and the wheels looked ... also OK, I guess, but not really great. I was thinking I'd probably just leave the hubcaps on.
Then I got the car and the hubcaps are very meh. Clearly big plastic hubcaps. Being dark really helps but in the end I felt like they look pretty cheap and kinda boring. But efficiency! presumably the whole point of them is aerodynamics and efficiency but how much of that is just academic? This is a job for science! (well Mythbusters-grade science, anyway)
So
@cwanja and I set out on a wild Saturday night road trip to make two loops around Houston and find out. We took two full loops of Beltway 8, which makes a ~92 mile lap around what was once a ring containing most of the metro area:
View attachment 705859
... It's reasonably flat:
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Charts and images are from Tessie, by the way (
Tessie: Awesome software for your Tesla). The spike in elevation in the middle is the bridge over the Houston Ship Channel.
The idea was: start by going to a Supercharger, charging to 'full' (which I have set at 80%), do a run with hubcaps, then while re-Supercharging, remove the hubcaps, and do it again.
The first run started around 9pm, so traffic wasn't nonexistent but it was reasonable for most of the trip, and we were able to mostly just stick with Autopilot engaged at ~73mph:
View attachment 705861
Efficiency-wise, here's what we got:
View attachment 705863
So a solid baseline. While supercharging, we popped off the hubcaps and installed center caps (
ROCCS Tesla Model 3 S X Set Airo Wheel Cap Kit) and lug nut covers (
VOSAREA 21 in 1 Hexagonal Wheel Lug Nut Covers). The lug nut covers match the wheel color reasonably well; they're a tad lighter, and not 'metallic', but the shade is pretty close. The center caps are not quite the right shade, and also came with several minor blemishes; I'd recommend looking for different center caps but the lug nut covers were OK.
Then we did the same route again. Traffic was a bit lighter, so speed was a bit more consistent, but overall pretty good: the route time ended up being almost identical, down to the minute (1 hour, 22 minutes each lap):
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You can see there's a bit less slowing down during this trip but overall it was very consistent. Energy usage was also remarkably similar:
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What I gather from this is that the hubcaps make no useful contribution to efficiency at 'average' highway speeds. The second run took slightly more energy, a whopping increase of 2 Wh/mi, but with a single run in each configuration I'd say this is potentially just in the noise. If I was going to compete at Le Mans maybe I'd slap the hubcaps on but in real life, they're staying off, and if I'm taking a road trip they're probably also staying off: it might mean consuming a handful of additional Watts, but it won't mean additional stops to charge, or even noticeable extra time charging.
Anyway this wasn't a really surprising result, but it feels nice to say that we at least know what we're missing by taking them off.