Yes, I've achieved super cavitation on my Tempo. A simple flap ahead of and behind each wheel keeps me safely on the road at most sub-sonic speeds. To take it to the next level I will mount a 6-foot pole to the front of the car, "jousting style", with a cone on the front of it. Think of it as "drafting myself".
There was a semi-recent piece re: I think that same phenomenon in Pop Sci; they were talking about underwater weapons and such?
Ah yes, here it is:
Supercavitating Torpedo | Popular Science
Ooh! Lookit what else was on Pop Sci:
A Cocktail of Diesel and Gasoline Runs 20 Percent More Efficiently Than Either One Alone | Popular Science
Could be kinda neat.