Maybe Johnny is vampire. We'll see...

Apparently, this was a real subplot that was dabbled with in the 500-page pre-film novelization of the movie, but here's a bit from some random site I saw:
https://www.factfiend.com/room-almost-flying-vampire-car/

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Specifically after bemoaning to a producer that a scene depicting a confrontation with a drug dealer wasn’t dramatic enough, Wiseau asked if it would be possible to use CGI to have the climax of the confrontation be his character’s car flying off into the sky. The stunned producer simply asked Wiseau "but why though?" to which he responded "maybe Johnny is a vampire".

As you've probably gathered given everything else we've said about him today, Wiseau never saw fit to explain to anyone on set why owning a flying car would suggest that his character was a vampire and had to be talked out of including the scene by Sestero. Wiseau eventually relented, though not before suggesting that they spice up the scene by having one of the actors fire an actual real handgun into the sky. When it was pointed out to Wiseau that this was all kinds of illegal he relented and instead gave the actor an airsoft replica pistol and told him to use it to scare the shit out of the other actor in the scene as he mugged for the camera.