They wouldn't acknowledged it as a common issue. I gave up after driving more than 4 cx5s with different trims. It's annoying but what can we do.
Reading back through this thread it looks like an ongoing problem on a new car and you're in Canada. I'm another with zero mirror vibration problems on either of my cx5 5's (2016.5 touring / 2019 signature).
I saw where you were taking your car to another dealer to investigate the issue. What did they come up with? Same answer I suppose ... Nothing wrong / normal. Odd how if this is normal how come it's only the left mirror?
The 1st dealer said they compared to 2 other new cars on the lot and they were the same. I see you said you drove 4 other cx5's. What did you find? Were the 4 others the same as yours?
As far as getting Mazda to make you happy with your mirror complaint I don't have many suggestions other than taking it deeper ... Complaints, arbitration, whatever consumer boards Canada has, etc.
As for a real world solution to make the mirror physically stop vibrating how bout trying some type of small piece(s) of foam wedged between the edge of the mirror and the housing. I'm thinking of things like packing peanuts, or squishy foam from an electronics box, piece of foam mattress, piece of "pool noodle"
Improvise, overcome and adapt
