TL;DR - stock 18" Aero covers and uberturbine-style covers, symmetric or not, all performed identically within a margin of error. I'm keeping the Kavanic covers on because they're no worse efficiency-wise, help protect from curb rash and especially painted, I prefer the look.
A couple of my first set of UT-style covers broke a couple hub grab clips the first time I removed them. That seller is no longer active on Amazon. After I asked, they did give me a 50% refund. I kept the remaining two good ones for spares and bought a set of symmetric Kavanics when on sale earlier this week:
https://www.amazon.com/dp/B0BJPYFR2R
I painted the Kavanics and the spares with this - one $7 can for each two covers:
Krylon K02782007 Krylon Fusion All-In-One Black Hammered 12 oz Spray Paint, Multi-Surface, (1 Piece, 1 Pack) - Walmart.com Very happy with the result. It has a subtle iridescent "off black," glossy and hammered look in the sun.
Assuming the paint itself doesn't affect efficiency, I then proceeded to carefully test the symmetric covers first as labeled (L and R sides), reversed left to right, and the stock Aeros. As others have mentioned, the way the "turbine" blades are shaped, it appears reversing them L-R would reduce air resistance, because installed as labeled a more blocked edge is forward with rotation. Controlled variables: ~9.3 mi loop course around KTIX airport, speeds 35-55 mph, 63-67 deg F, light wind, tires 44-45 psi, climate control off, starting SoC 38-49% with ~5 min L2 charging "break" between runs. Firmware 2023.38.6 (night) and .38.9 (this morning). Traffic was light and I was able to drive each one almost identically. Autosteer was enabled everywhere possible and over the same segments. I chose this course because it's representative of 90% of the driving the car sees.
The car's indicated wH/mi for each drive is different from what Teslamate recorded. I trust the car's numbers more than Teslamate because they vary less and there's no apparent rounding going on. Last, attached is Teslamate detail of each drive and a pic of one painted cover - albeit on a cloudy day.
Run/Drive # | Description | wH/mi from car (this drive) | wH/mi from Teslamate per drive |
1 | Uberturbine covers as labeled LR - night | 181 | 183 |
2 | Uberturbine covers reversed RL - night | 179 | 199 |
3 | Stock Aeros first run (tire warm-up) - morning | 188 | 197 |
4 | Stock Aeros second run - morning | 183 | 183 |
5 | Uberturbine covers reversed RL - morning | 182 | 199 |