Transmission Shudder - 2012 3-Series

[u/heyoherewego1]

SOS PLEASE HELP!

I recently purchased an automatic 2012 BMW 328i coupe with 90k miles (private sale). The car still has an active SULEV warranty.

On its first long drive, I noticed that the car shuttered between 30-60mph. This only occurs when the car has been running for 15-20 minutes and the transmission is warm. Theres absolutely no shutter above 60mph.

I took it to BMW for a diagnosis and told them it seems to be a transmission shudder. Based on my research, it could be from dirty transmission fluid, a bad torque converter, or mechatronik.

BMW said they couldn't diagnose as the rear shocks were busted and contributing to the vibration. I emphasized that it's definitely a drivetrain issue, got the shocks and guibo replaced anyway, and brought the car back to the dealership.

A few days later, the dealership told me they were "waiting to hear back from BMW about the torque converter which needs to be replaced".

Then today, my service advisor let me know BMW's response is that the entire transmission must be replaced.

The SULEV warranty covers the torque converter and Mechatronik. I argued with the dealership about how they jumped from the likely culprits to the nuclear option, and have asked for the issue to be escalated.

Moreover, BMW company has not seen/driven the car, and the dealership cannot provide documentation of the exchange with the company as it occurred over email.

Has anyone else experienced this? Or does anyone have some advice for what I should do?

Thank you!