In Knight Rider, the 1982 TV series, did KITT have seat belts? I don't recall to ever seeing them. Michael never fastened, did he? Sport belts in the pilot "Knight of the Phoenix" don't count.
KITT evidently had lap belts for the front seats (or at least the front passenger seat), although not the shoulder belts that were standard in the 1980s. This can be seen in "The Final Verdict" (season 1, episode 11). Here is the teaser, in which the relevant scene appears.
Michael is shown trying to get his nebbish passenger's lap belt fastened. The belt itself is not in view, but it is clear that it is there.
It's clearly revealed in the second episode (part 2 of the pilot) that KITT has front seat belts, apparently with shoulder straps, not just lap belts:
Note the restraints visible in the front passenger seat, and Michael's admonition to Buddy:
"Now get in that seat right now and strap yourself down!"
It seems safe to conclude that there aren't any rear seat belts, or Michael would've told Buddy to buckle up in back instead of having him crawl into the front.
In season 3, traditional seatbelts became irrelevant with the introduction of KITT's Passive Laser Restraint System, which utilized a series of non-harmful lasers that would cover a portion of the occupant's body to prevent jarring in the event of sudden turns and stops.
Though it was never mentioned exactly as such, it's speculated that the PLRS was an extremely early version of what's come to be used in Sci-fi starships such as the Enterprise in Star Trek's "Inertial Dampeners" technology, which requires NO physical restraints to reduce the effects of G forces.
It's how the Enterprise and other starships could accelerate to full impulse or warp speeds without leaving the crew splattered against the bulkheads.