Unfortunately, there aren't many 1/8 scale models of any kind, old or new.
As far as older American cars, here is what I remember;
'27 Ford Big 'T'
'32 Ford Big Deuce (Now reissued)
'65 Corvette
The Trans Am and a few Corvettes, and an IROC Z-28 from the mid eighties if those are old enough.
What did you have in mind?