Havent tested my 3 day old SX AWD yet on highway but will do so tomorrow when we go on a road trip. Here's my two cents after reading this...(and thinking about it overnight
-Appears to be an issue on certain SX-AWD (here in Canada all trims are AWD). Interested to see if its a EX vs SX issue. (major drivetrain difference being 18 vs 20 wheels)
-Dealers in all their wisdom will try to eliminate common causes (and cheapest/easiest fix) - balance tires, blame road conditions etc. Likely all of the tech's are learning on the job. You'll get better results from larger dealerships that have 2020 Telluride "specialists" ...everyone is learning on the job with a small sample size out in market. They will do everything they can to NOT open the tranny or deal with real drivetrain issues. The best you can hope for is they ride along are able to "replicate/observe the issue" and agree its an issue worth escalating to the manufacturer. I wouldn't expect them to open the tranny or do any meaningful fix. You hope a smart tech can diagnose and help put a fix and feed it up to corporate who can dessiminate to the dealer network as a service bulletin. (or we can do that here).
-From the sounds of the issues its clear there is an engineering/design/assembly issue here. Given its not systematic its likely assembly or quality related. Because of the speed band (seems to be a 65-75 MPH) range i agree with the assessment of some sort of unfavourable drivetrain harmonics is the culprit. usually imbalance is consistent and is a linear progression as speed/force increases and does not appear/disappear. Harmonics issues are related to a convergence of frequencies / waves and usually evident in a certain range only. (confluence of events)
-Given the fact that the transmission is used on other models is a closed system unless this is seen on other KIA/Hyundai models likely its not a tranny issue but rather something between the tranny and wheels. trannys are usually tightly engineered but assembly issues do happen esp a "bad batch"
-It would be useful to figure out whether this is a rear or front wheel or mid-chassis issue to further isolate...where is the vibration coming from?
-could also be something related to wind baffling occurring. (think about how you open sunroof with all windows up). the wind hitting an object or unfavourable wind circulation at that speed could cause these "harmonics" to occur. at the right speed and conditions it may set off some waves that bounce off objects in the undercarriage/wheel wells that elicit this sort of vibration. bad aerodynamics too. maybe try to isolate where the sound is coming from?
-would be useful to see what other kia models have experienced this if any to compare
-given it seems a serious issue the best is for everybody who experiences this to report to dealer, squeaky wheel gets the grease! and then KIA engineering will put a team on it and find the real fix.
-I just got mine delivered in Canada a few days ago and build date was May 29. I believe the earliest dates of assembly I saw was late Jan 2019. Its still a first year model and May builds are considered mid-late cycle.
ok thats all thats in my head.
(People who don't buy first year new models may now comment below....)