Being used but very well-made vehicles, the P5 appealed to me as on-par with the newer Mazda 3.
Very zippy, quick-feeling little car. Not the fastest or best handling, and a bit unrefined, but lots of fun at moderate speeds- you feel like you are going faster than you are, and having a blast doing so. Very entertaining on a daily basis.
Both the real-world reputation, and that Mazda is active in motorsports (except Nascar, but I HATE Nascar, so that exclusion is a plus for me.)
Built on the same assembly line that Mazda originally slated for their up-market line (to compete with Lexus, Infiniti, BMW, etc.)