There aren’t any lemmy.ml communities with “mazda” in the name:
https://lemmy.ml/search?type=Communities&listingType=Local&q=mazda
In order to access non-lemmy.ml communities from lemmy.ml, you do: https://lemmy.ml/c/COMMUNITY@INSTANCE
So, for instance:
https://lemmy.world/c/mazda ⇒ https://lemmy.ml/c/mazda@lemmy.world
~~But note that, because no lemmy.ml users have yet subscribed to the !mazda@lemmy.world community, it will appear to have no posts, even though it really does have posts. You or some other lemmy.ml user must subscribe to the community in order for posts to start federating.~~ [It looks like someone has subscribed after all.]