car vibrates and shakes a lot when cold when the transmission is on D or R but fine when neutral, and also when changing transmission from D to R or to N a sound from the back of the car comes like a bang this happens every time even when hot, i went to the workshop and they told me that there is a problem with transmission and need to be fixed and it will cost $3000 at least but i didnt believe them, because there are no problems at all when the car is moving.