Over the past year, we’ve been bringing you spy shots of the upcoming Toyota Supra and its BMW counterpart, the Z5. This week, our spy photographer has sent us the most revealing photos yet of the German version of this joint sportscar venture between Toyota and BMW.

Caught cold-weather testing in the Arctic Circle, the BMW Z5 Roadster prototype is seen wearing less camouflage than before, and the photos now reveal its rear. You can see the design of the taillights, as well as the central brake light on the deck lid. The tester still wears a bit of cladding, especially over the doors, so we’ll have to wait a little while more to get a glimpse of the production body.

But what’s certain is that unlike the most recent Z4, which had a metal roof, the Z5 will come with a retractable fabric top. Powertrain options will likely include a turbocharged 2.0-litre four cylinder and a turbocharged 3.0-litre inline-six. And since it shares its platform with the Toyota Supra, a hybrid version is also likely. Chances of a full M version look slim at the moment.