That bit is misleading since you don't have a default constructor.
Surely manufacturer and number of passengers are attributes of the Vehicle class not specifically the Car class. You may wish to make passengers default to 0. Or, if I read the post correctly, it reads doors. Again you may wish set a default number of doors. 0 is permissible. I can see no point in passing a superclass object to a subclass' copy constructor, except under the following rubric:-