Coming up for five years on my 2017 Mazda 6 GT, with tech and premium package. My my how time flies.
Not a lot of miles on it yet. Coming up to 32,000 Kms, which is just shy of 20,000 miles.
No real issues yet. Heated drivers seat stopped working two years ago and was fixed under warranty.
Biggest concern is rust and poor paint. I had the roof repainted last year after a few bubbles showed up (warranty repair). Rear brakes are rusty and need replacing, but I haven't gotten around to it yet.
As for performance, that is it's strong point. It is a pleasure to drive, and hasn't let me down.
I also still think it's the best looking model year of the latest gen Mazda 6. I didn't like the changes they made in 2018 and up, (although a turbo would be nice).
I try not to drive it in bad weather, winters especially, and garage it most of the time. It will be in the family for a while yet.