I guess these are tall tales or "urban legends" both tales i have heard many times but the one with the war veteran is so very popular that most care cruises will have at least loud mouth who insists is was a family member or close friend who either died or bought the car cheap.
The first involves girls 2 or 3 in an old air cooled volkswagen beetle, florida is full of sink holes that become lakes and natural springs the springs are great for mining fossils,
so depending on the version of the story the beetle drives into a sink hole lake and vanishes, then at some point later a beetle is found in another lake with human skeletons inside,
or the car pops up in a spring, another version is the car acted as a diving bubble and the girls survive but are found in a lake or spring many miles away we are suppose to buy that the car was in some under ground passage, some versions include the girls turning on the headlights ( which would work a short time underwater ) and saw the creatures that lived in these passages.
i find that story total rubbish.
the next, might just get a hit on here, someone might just say they know where it did happen, like always prove it, it would be cool.
a young late teens man in 68 is getting drafted to fight in Vietnam, so he goes to a car dealer ( not sure where he got the $$$ ) and he buys a new car, the make and model change but its always something thats rare and desirible in todays cruiser gearhead world,
so the kid drives the car only a few miles parks it in the garage goes to war and sadly dies,
his greving mother covers the car and forgets it, then a few decades later a guy who is there in her garage usually for some good Samaritan reason asks about the car under the tarp, she teary eyed tells him the story and he offers to buy it,
depending on version the car is sometimes a gift but always dirt pennies on the dollar cheap, the happy new owner then jumps in a car that been sitting neglected all that time and drives it home.
while perhaps somewhere a greving mom sold a passed sons car the ridiculous embeliments are what makes the various cruise spot verions so endearing.