Hey, it's awesome that you show interest in helping the wiki out but please keep our rules and style guide in mind. Regarding your creation of the 1.12.2 page, this minor version has not been released and almost no official information regarding its content has been released (not enough to warrant a page). Because of this, 1.12.2 should only be on the Planned versions page. A redirect to this section is fine but that's it.
Regarding your creation of the Car page, this term is not used in Minecraft (or by the community) and therefor has no place on this wiki. Even if it was used as a synonym for Minecart (which it is not) it should be redirected to that page instead of just copying the whole page over.