2024 Hyundai Sonata Cruise Control Problems

Hello, thanks for reviewing. I recently bought a brand new Hyundai (VIN provided) and the speedometer intermittently is inaccurate. Maybe 50% of the time, which I would argue is less safe since I can’t reliably tell what my speed is. When it is an issue, it’s worse the faster I drive. It breaks the 10% threshold I’ve read about around 30mph, where it will say 26mph. I brought it to the Hyundai dealership and they claimed they couldn’t replicate the issue so they won’t fix it - but it’s intermittent and I have picture / video proof from multiple dates. I used various speed sources to be sure. I found some Hyundai forums online where many others have the same issue. The speedometer is an important safety feature, not to mention other dependent features, like cruise control. Happy to provide proof by request.

The vehicle speedometer is occasionally 5mph off. When I first get into the vehicle after it’s been sitting for a while and drive around, the speedometer works perfectly. If I shut the vehicle off while getting gas, running an errand or something similar that involves the vehicle sitting for a semi-short period of time, the speedometer will be 5mph off when driving. I initially detected this issue be noticing that my speedometer was different from the speed posted on a GPS based speedometer on my phone, who’s speed exactly matched those road side speed measuring signs found on the highway, but both of those measuring devices differed from my vehicles speedometer. I brought my vehicle into my local Hyundai dealership who verified the problem exists, but mentioned that this was a software issue which needs to be corrected my Hyundai Corporate. I contacted Hyundai Corporate at the number provided to my by the dealership, and was essentially told that there is nothing they are willing to do to fix the issue.

As I’m driving 75 MPH, my car slows down and on the dash board it reads 20 MPH LIMIT. I’m on the Expressway and, prayerfully, by putting on my HAZARD BLINKERS, I pull over, wherever it’s safe, turn car off, restart the car and then it’s fine. PLEASE HELP BECAUSE THIS IS A LIFE THREATENING SITUATION! SCARED This has occurred SEVERAL TIMES.. Approximately 1 month ago I took it into SERVICE DEPARTMENT (kept 1 week and never slowed down on them. Again, once the car is turned off, it drives fine. How can I turn off this 20 mph hour limit on dashboard. Any advice or help you can give me to put me at ease, is CRITICAL! Thank You in Advance.