Are you talking about aero wheel covers?
They would need some means to attach to the alloy wheels.
The car is such a 'box' and only 82 miles to measure an aero improvement.
I doubt you'd be able to get consistent data.....
Used '14 2LT w/ DCFC. +76 K miles.
Mostly free charging! Only one LONG visit to the shop....
GM needs Modern Troubleshooting tools for Modern EV's.
3 step Trouble Tree, 2nd guess not covered by warranty and cost $800. 3rd guess fixed the problem.