I did a little 120 mile experiment to answer a long standing question I have: Do the Aero wheel covers matter for the kind of driving I mostly do? So, on a hot lazy afternoon here in the desert Southwest, I did an experiment testing that out. I figure the results are worth sharing.
Weather? A hot, lazy afternoon, temperatures ranged from 86-88 degrees F during the entire driving experiment. Winds were light, about 10 mph, with occasional puffs up to 20 mph. Relative humidity was like 5% or so. Car had been driven around doing errands before the testing, the tire pressures----cold = 42 psi---during the test yesterday were 46 psi (plus or minus 1). The car's state of charge/range read around 220 miles and I ended at 150 or so.
I drove the exact same 29.9 mile loop 4 times. Nice music, an occasional deer or three, mountains of course, and the skies were pretty. The odometer matched exactly on all 4 loops. First loop was with Aero caps ON, next with Aero caps OFF. Took a brief restroom break and then took the 3rd loop with Aero caps ON, then finished the 4th loop with them OFF. The route consisted of parts of NM-4, I met very few cars during the experiment; I basically had the road all to myself. The speed limits range from 55 mph over one long stretch, to another 50 mph long stretch elsewhere and mountainous driving elsewhere. The remaining parts of the loop consists of sorta residential driving, from 25-35 mph. I used the cruise control to maintain my speed consistently during the whole trip and I didn't touch the climate control the whole time either. I had climate set to manual, and at a fixed fan speed to stay comfortable. Never messed with it during the whole trip. Altitude variation is from 6500 to 7500 ft. I reset the "trip" odometer just before starting the trip each time and recorded the results exactly the same upon my return to start.
Loop 1, Aeros ON, 185 Wh/mi
Loop 2, Aeros OFF, 187 Wh/mi
Loop 3, Aeros ON, 180 Wh/mi
Loop 4, Aeros OFF, 181 Wh/mi
Conclusion. For my kind of driving, Aeros ON vs Aeros OFF doesn't seem to matter. Some day I'll try an experiment at highway speeds (75 mph).
Observation. I THINK that the ride was quieter with the Aeros ON by the way. I swear some of the wind noise was gone with Aeros ON. But that's subjective, just my humble opinion.