The intent is probably to hope that the ref has never seen an At-om. If they think it does not resemble a previously manufactured car, it should go to 1960 automatically. However, if they do decide that it looks like its from the 1990s, you're kinda SOL.
Basically, it depends on interpretation- does it mean a)typical of the time period (and what makes it typical), or b) like something from that time period?
Here's an At-om:
http://www.lotustalk.com/forums/f152/ariel-atom-16745/index2.html#post291240And somebody's page about registering his At-om in CA
http://www.andysatom.com/legal.html Doesn't tell much detail though