The biggest mistake in a very good cartoon

[Flangepart]

Ulthar : Prince planet? Woah, thats new to me. Makes me think of a world full of Prince of Space wannbes. ::o

[ulthar]

I loved that cartoon when I was little; it was my favorite.  You can find more about it searching for the original name Usei Shonen Popi.  Here's some more info on Prince Planet from the planet Radion:

On the Prince Planet Page there's not much info, but you can see a good visual of Prince Planet.  You can certainly see the visual similarity to the characters on Speed Racer, at least in the face.  The graphic looks like I remember except for one detail: the medallion should have a black "P" on it (maybe it had a star like is shown on the reverse).
IMDB Main Page
User comments on IMDB has more info than main page
Good Prince Planet page with plot and production details.
Another good Prince Planet Page

He wore a "P" medallion around his neck from which he got his energy.  When he needed his 'powers,' he would yell "P...for POWERRRR."  The P on the medallion was like a power meter, and if the P got empty, his powers would be gone.  This was when you always thought the bad guys would finally get him.  I don't recall what he had to do to recharge.

From the user's comments on IMDB, it looks like it the only people who remember it from the US were in south Florida and Chicago.  I watched in south Florida around 1971 or maybe even before that.  IIRC, and this is really cobweb memory stuff, I watched PP before Speed Racer was on (at least where I lived).

Truly an obscure animation produced in the 1960's (aired in the US 1970-1971).