https://youtu.be/QHjw7U0WLOQ
At 21 seconds you can hear the grinding sound from going into 2nd gear from third gear. The second scene shows a test from flooring it in 6th gear on the freeway - no slipping here. The third scene shows flooring it from 6th gear on a hill. In the third scene the car immediately dropped below the idle rpm and didn't 'slip'.