As far as I know, I think he was in a Battlestars commercial. Taking a quick look at TFWiki, that form was also used in the 15 Go! Go! manga, but beyond that, I'm not sure.
Thanks. Wow, took a bit to find that Go!Go! info. I thought there was some fiction around the early 90s Japan explaining his MM form, but I guess not.
He was used in a now defunct fan comic called Superdeformers. Which is funny official or not MM Hot Rod doesn't seem to have been used much.
I do feel World's Smallest Hot Rod makes a good substitute. He doesn't look out of place with actual Micromasters.