When I drove the Kia EV6 a few months ago, while the overall experience was remarkably good, the vehicle did stop heating the cabin on a couple of occasions (this has now been reportedly fixed) and once it emitted a very strange high frequency sound that I could hear while performing a low speed parking maneuver. That was the only time I heard that sound, and I though it was just one of the car’s systems at work, but apparently the vehicle shouldn’t make that sound and it's a nuisance to many owners.
According to the Korean Car Blog, which quotes a local Korean news report from the KBS TV news channel, this is a common problem and now Kia is looking into it. According to the source article, the noise is audible when the vehicle has been driven at around 30 km/h (18 mph), then slows down.
The sound is described as a very noticeable beep, although if it’s the same sound that I heard, you may not be able to hear it if you have music on in the vehicle. In some cases, it goes away, but some drivers report having to crank up the music to drown out the sound.
KBS brought in an expert with a sound detector whose specialist gear was able to pick up a sound at around 6,000 hertz, well within the range of the human hearing spectrum. Apparently, it’s the fact that the EV6 is electric, so it’s very quiet plus it is very well sound-insulated, so even if the noise itself is not especially loud, it can still be an annoyance.
One of the EV6 owners interviewed by KBS says that he now hears the sound even when he is not in the car. He says it has been ingrained into his brain and that he now feels like he suffers from tinnitus. Kia has so far not made any public statements acknowledging the problem.