Ah nostalgia... it's such a nice whitewash of reality. So I just went to see how much a Hotwheel (or Matchbox) STP Turbine car was worth. Answer: nuthin'. They don't exist. No such thing.
However... there was a Shelby Turbine that bore a familiar likeness to a certain Indy Car sponsored by a company whose initials sound almost, but not quite, like Sexually Transmitted Disease.
Humph... Shelby Turbine. Right.
On the plus side, I just discovered that the Beach Bomber that sits on my desk that I had since I was seven is probably worth $100. So I've got that going for me.