i bought that pen. as i read m3 owners were using that to paint the exposed part of the wheel. upon closer read of the reviews i do see some people saying they used it on the hub caps. was hoping to hear from some forum members.
For what it's worth. the dupli color pen works great for the actual wheels. it's not exact but it's close and better than leaving the curb rash as is. It is not a great match for the aero covers however. just my opinion. i wish there was a better match. Paint matching the wheels is more forgiving than the aero covers.
Another option is to just purchase a new wheel cover at the Tesla parts department. They are located within the service centers. I believe the price is only $30.00. Not that much more than touch-up paint.