The barn stories of (fill in the car) the guy who left for Vietnam (always 'Nam!) and never came back for that one-of-x whatever musclecar. It's either in pristine shape (after 40 years in a non-climate controlled environment!) or it has deteriorated to the point where the guy's dad/mother/brother/uncle/cousin just can't (or won't) let it go.
Another is the one (for you Mopar fans, like me!) where the police department/state patrol/sheriff's office ordered up some HEMI-powered cop cars (NONE were EVER built by the factory at any time, nor custom-built or dealer-converted, in case you did not know!) and the story is always from the guy who swears he'd seen the car for himself. Another Mopar story is the long-lost one-of-one HEMI pickup built from '66-'71 sometime, of which there was none. That and the mysterious HEMI wagon, too!
The weirdness continues.