I'm no expert in object oriented programming, but I would think that for example the VehicleDealer class doesn't need any attributes belonging to a car or Motorbike. Instead it will delegate those details it gets as a parameter to the VehicleBuilder which in turn delegates to the CarBuilder. And the CarBuilder will at last call new with those parameters so that the attributes are set. Only the car class should have an attribute like outside color or inside color, while the Builders might have methods like paint or configure.

Check out the wikipedia example Builder_pattern. Note that only the actual pizza has an attribute dough. Ok, the builders have a method for every attribute. if you want to avoid this, one method would handle a group of connected attributes (i.e. if you specify outside color green, the method knows a default matching color for the inside).