The system that is not working properly is the transmission. It is available for inspection upon request. The safety of the vehicle, and myself, was put at risk because the transmission (once warmed up / at least 30-60 minutes of driving takes place) downshifts hard, making a clunking noise, and has at worst given the vehicle a rough nudge/jolt forward upon downshifting particularly from 2nd to 1st gear (it is a 10 speed transmission). This issue, when it occurs, will require me (the driver) to apply extra force to the brake pedal due to the rough downshift / jolt upon shift. The issue is exacerbated when quickly stopping the vehicle causing the transmission to downshift more rapidly. The vehicle’s transmission flaws, of which this happens to be one of them, were being looked into at a certified repair facility (dealership). After the vehicle was in their possession 3 days, they informed me that they could not replicated or reproduce the issue. I informed and reminded the following: (1) the vehicle has to be warm and operated for I would state at least 30-60 minutes of driving before the issue arises (2) I have recorded videos of the problematic sounds of the transmission. (3) I am willing to go for a test drive to try to replicate the issue with dealership staff, but the issue is infrequent and the vehicle must be warmed-up and/or driven more than the typical ‘test drive’ for the issue to be observed. The vehicle component has been inspected by a certified repair facility (dealership), but not directly by a manufacturer’s direct representative, police, insurance representatives, or others. The transmission is also problematic in another way (rattling at low rpm’s during upshift), but pertaining to safety the downshift is most concerning as described above. There were/are no warning lamps or messages. The symptoms of the problem pertaining to the transmission began occurring around 11,800-12,000 miles in my estimation.