Never thought of that. Time consuming unless I knew to look at the card, but interesting idea.
Here (in my local area) they use mostly sand with a mix of some salt.
I haven't seen these cars before. I see many regulars go by to a local car show every Thursday, but we seem to be on some sort of route because we see a lot of different old cars. And it's not like I stare at the road, so we must be some inbetween point. I've seen barn finds on flatbeds and a few old cars on their way to work. I can't complain.