I thought it may have been an old TVR, but the ones I've checked out have a different angle on the front edge of the rear window and no sign of that vent. Wait a moment. Is it my imagination or can I see a role cage inside?
It's clue time.... been up for almost 3 days now, and no one's got it. I have no idea. I also was thinking TVR Vixen/Tuscan from the 70s, so I'm also out of ideas.