I have a 2018 Sonata Limited 2.0T. Ever since I purchased it, I found out that the Premium Infinity radio's TREBLE control doesn't work at all! I later noticed that this problem is in all vehicles that feature this same Infinity radio (2018 and 2019 cars). The treble slider moves from -10 to +10 on the display screen, BUT THERE IS NO CHANGE IN THE HIGH-FREQUENCY SOUND! HYUNDAI refuses to get Infinity to fix this. I have had my car since October of 2017! Still no software update for the PREMIUM INFINITY radio! Terrible QUALITY CONTROL at infinity!