With the caveat that all I know about Hot Rod comes from the 86 movie, how was Mirage in RotB literally anything like Hotrod? Hotrod in G1 was the "youngster" and a bit of a hot head, but his personality was nothing like Mirage in RotB, who seemed like he was more of a "young cool guy" archetype, with a bit of a streetwise style personality and a lot of wisecracking, which I don't associate with Hot Rod. Not that TLK's Hotrod was particularly like Hotrod either, but at no point watching RotB did I ever think of Hotrod when watching Mirage. Of course there is a whole season of the first cartoon after the movie with Hot Rod, and other continuities so maybe he is more like that in later incarnations, but I just really don't get the connection between RotB Mirage and Hot Rod, outside of both being treated like the younger/less experienced guys by the other Autobots.