I recently bought a 2006 Mini Cooper S. I've noticed the longer I drive the worse the shifting gets. When I first get in the car shifting is fine but after about 10 or so minutes it will either jerk really hard or the RPMs will go up a lot before it shifts. I've heard a few a few different theories from it being my turbo, clutch, or transmission. I took it to the dealership for something else and asked them to check it out and they said everything was fine. Just curious if anyone has any idea what it could be or some tips and what I should do.

Thanks