The thing I really love about those old "numbered" Apollos, is the very simple (by today's standards you might even say naive) marketing approach. Like "what is an Apollo II?", "Well that's a little bit better than an Apollo I". "So what then is an Apollo III?", "Well that's a little bit better than an Apollo II".
You get the picture. Works ok until your competitor starts naming their base level bike the "Dominator 2000"