This one seemed to be a bit tougher, but a couple of people did guess correctly: it's a Glas GT. A reader from Norway hit the nail on the head by telling us "the car in the photos seems to be a Glas 1300 GT or 1700 GT. The characteristic shape of the badge (or rather what´s behind it) is
evident in the photos. That is why it can´t be one of the later BMW-badged 1600 GTs."
Check back for more mystery cars.