I have same issue wiv my yorkshire too ...
we got her as a puppy around 8 months ago and in her life maybe she barked 5 times . she never cries , lets say i put her in a room so she sleeps she might come next to the door and cry for half a second and thats it . this is not our first york and all the other yorks we had used to bark even at themselves caz they are barking .
she also is so scared of cars i cant really understand why , she starts shivering if i put her in a car , at first i used to think caz of the weather but now we are in June and its 30 degrees and she still does it . so its very hard for me to take her to another city .
when i drive i see dogs in cars out of the window enjoying the wind and i wonder why my dog aint dog . maybe she think shes a cat ?