Continuity mistake: Even after KITT's voice modulator changes to the three bars in the episode "Hearts of Stone," any shot of KITT starting himself up still shows the old voice modulator (a simple red square).
Continuity mistake: In the first few episodes watch KITT's glowing square. In some scenes the flasher says KNIGHT 2000 and other times it does not.
Answer: I would say that unless there's visual evidence it was another K.I.T.T. car, as in you could see the bar scanner or cut steering wheel, people on here would correct the mistake by saying more than one 1982 Pontiac Firebird Trans-Am was sold and there's no reason it's meant to be a random car.
Bishop73