I lost my link to it and it's taken ages to find it again (I just needed to omit US from the search terms!), so I'm leaving it here in case I lose it again:
It's photographs, not just of cars, but trucks and vans too. They're all old, but some are extremely battered and decrepit. They were all photographed in Portland from about 2009 onwards and they're by no means all American. I hope someone else likes the site too!