Ahh easy easy. The planet was ruled my HOMO - SAPIENT type people. The queen one day was brought a gift statue from one of her peasents... it was a metallic man. LIttle did she know the gods struck her with love for this metallic being...and she had relations with him and thus little baby mettalic guys came out ... then one of her kids.. saw this car.. and thought the car was really sexy.. so they got married and had baby mettallic people cars.. and thats how it started.
ok this sounds perfectly logical, but I just have *one* problem, how'd they get so big? wouldn't they be like human-sized when in anthropological form? And then like miniature car-sized when they're vehicles?
because the mother of all these things had great super amazing mammary glands that produced a milk that was like castro gtx for this things and made them grow big and strong.
ahh. ok. It all makes sense now. thank you, i like birds.