Yeah, I remember my parents, Granddad, etc, talking about cheap cars they got back in the day. My Mom's first car was a 1957 Plymouth that she bought for $75 in 1965, when she was 16. She doesn't remember much about it except that it was big, it was gray, and one of the windows shattered once when someone slammed a door. Of all the swinging, groovy color choices available back then, leave it to my mother to find a GRAY car!

But she drives a white Altima now, so at least she's stayed true to her roots I guess.
When I was about 3, my Granddad found a 1964 Ford Galaxie 500 4-door sedan with a 352 that someone was willing to GIVE away. I think it just needed a new starter. Back then, my Mom was driving a '68 Impala and Dad had a beat-up '62 Corvette with a stick shift that Mom couldn't drive. Well, Dad had a habit of taking Mom's car and leaving her stuck at home with a car she couldn't drive. My Granddad got this Ford and got it running with the intention that my Dad would drive it, instead of Mom's "good" car. Didn't happen. :

That Ford wasn't in bad shape, just an out-of-style car that nobody really wanted anymore, even though it had plenty of life left in it.
Back then the styles changed so much that even though a car still probably had years of service left, the styling was just so outdated that nobody wanted it. Mom's '57 Plymouth was a perfect example. The car whose ads proclaimed "Suddenly it's 1960!" (style-wise, it WAS about 4 years ahead of its time in 1957, and the Mopars that year made everything else look downright ancient) looked really outdated by 1965, with its wraparound windshield, towering tailfins, chrome, headlights above the grille, etc. Similarly, that '64 Ford, with its trim, crisp styling just looked out of date in the 70's, when cars were getting bigger, fatter, "hippy-er", pimpyier, etc.
So I guess if you took something like that free '64 Ford or that $75 Plymouth, just let it sit away somewhere without really doing anything to it, and then maybe getting $1000 or so for it today, THAT would be a pretty good return on your investment!
As for the '62 Corvette my Dad had, I think he paid $1000 for it. I'd guess a '62 Corvette with the right engine these days could go for $60-70,000 or more. But this was just an old beater, even back then, and I don't think it even had the correct engine in it.
After the Corvette, Dad got a '64 GTO 2-door sedan, which he paid around $350-400 for, around 1973 or so (about the same time we got the Galaxie). It was another piece of junk, and its engine blew. My Granddad helped him put another engine in it, a Chevy 400 I think, which pretty much killed any value for originality. I guess a '64 GTO 2-door sedan with a 389-TriPower might be worth something nice, and a hardtop or convertible would be worth way more, but this thing was just a rat-bastard.
As for cars being assets though, I'd say that they definitely have SOME value. Just don't expect to make money on them. And they're not something that can be sold quickly and easily to raise cash. For instance, I might be able to get $7-8K for my '67 Catalina convertible, and maybe the same for my '57 DeSoto. But if I needed that money say, tomorrow, I'd be SOL.