Maniacal

What's wrong with the word "maniacal?" It's as fine a word as any other, yet I've been questioned about both its meaning and its existence. But what's so confusing about the word "maniacal?" It's merely the adjective form of the noun "maniac." That's not to say that I hear the word used all the time, but it's still 100% valid. My usage of said word dates back to my childhood when I was a big fan of the movie "Who Framed Roger Rabbit." Now, I'm still a big fan of the movie, but I was then too. Anyway, at one point, when Judge Doom is chasing down Eddie Valiant, he empties a barrel-full of the dip, his patented toon-killing concoction, onto the road right in front of where Eddie is passing by in the toon-cab Benny. Benny's tires get damaged by the dip and he ends up crashing into a pole. The judge mercilessly makes his point by saying, "What an unfortunate accident. Nothing more treacherous than a slippery road, especially when driving in a maniacal toon vehicle." Christopher Lloyd's voice is just perfect for this role. So I'mma keep using the word "maniacal." Preeeow.