The interior electric chromic mirror with HomeLink system automatically adjusts, controlling the glare from the headlights of vehicles behind you at night or in low light conditions. I do not believe that the exterior side mirrors dim at night, but as yet, I have not had a need for them to dim. When backing up the side mirrors automatically adjust downward to give you a better view. When locking the car the side mirrors automatically fold in against the vehicle and open as you approach the vehicle with the key fob.
So I just went out and parked my wife's car behind my Telluride and it does not appear to have auto dimming side mirrors. The rearview mirror is auto dimming but that's it on my SX. I had this feature on my Jeep Grand Cherokee and to be honest I just assumed the vehicle had it. So far that is my only complaint though and I would imagine at some point someone will have aftermarket inserts available so it can probably be fixed in 6-8 months.I ask because the exterior mirrors on my 2017 Honda CRV Touring model do not dim with the interior auto dimming mirror and that bugs the heck out of me. Some of the headlamps out there are very bright and shine right in my eyes when the mirror is adjusted properly. I found no mention in any specification of the exterior mirrors for auto dimming. The dealer I asked said they did auto dim, but she had no SX to check out. That is why I am asking you owners to confirm or deny the existence of the feature.
I agree, its kind of crazy to put so much into a vehicle and miss something like this. I am currently working on a letter to KIA about a few recommendations. Not deal killers for me but a few things I would have liked to see is Auto Dimming Side Mirrors, frameless rear view mirror (even Mazda does this) accent lighting around the cup holders and head rest that move just 3-4 inches forward and after (the RDX has this and its awesome). Maybe they will take it into consideration for the next iteration of Telluride at least.