2024MX LR delivered 3/1. My experience is the exact same (both in terms of the car and all I can think about). I loved my TM3 and told everyone it was the best purchase I ever made. I don't feel that way at all about this car sadly.Wanted to check in and see if this fixed your seat-back vibrations long-term? Specifically the ~30-60mph rumble/vibration. It's all I can think about - it's like a sickness.
And vibration is how I would describe it, really. Over smooth roads (nothing is perfectly smooth) it is a fairly high frequency shake/vibration/disturbance right through the seats. Passengers can feel it, too, so not specific to the actual seat itself.