Posts shown based on their category – how to make "next" & "previous" work?

On my blog when a user filters all posts from Category “Cars”, they are shown all posts with that category.

Say they click on post #1 in the category “Cars”, how can I make it so that the “Next Post” and “Previous Post” ONLY show posts that are within the category “Cars”?

Seems to be simple.. but I can’t find a solution.

Thanks!