The thirties and years that followed were awful tough on many folks. Doodle bug tractors showed up built from car parts. Cars were cannibalized to keep other cars running and few things were really discarded but rather saved just in case they could be used. A pile of metal on the farm was a resource for material.
Too in time, two world wars and their effect on resources taught many people to use stuff up till it was not fixable, then use it for something else. That old car or cars on your site was not forgotten and just dumped, someone knew right where it was if needed. War efforts collected such materials at times too so many such items were hauled away.
Part of history. Here is a couple articles that make your find a survivor, possibly saved for a reason....
Scrap metal drives - World War II on the home front: Rationing
Rationing on the US Homefront during WW II