More on the Tada roundtable in Geneva here:
https://www.roadandtrack.com/car-shows/geneva-auto-show/a19179702/toyota-bmw-partnership/
He talks about how initially they were looking to maximize the sharing of parts with BMW and then how that became less of a priority.
If there is no manual offering, the auto they use will have to be flawless. DCT would be best for finessing the inevitable criticism they will get (hell, they are already getting it in the auto blog comments).
Looking closer at your second image I see you've left some of the black banner across the top of the windshield which makes it appear a bit shorter in height than it really is.
The suspension setup will likely differ substantially between the two, with the Z4 being a softer GT and the Supra a true sports car. Plus the interiors are going to be completely different.
No doubt as the major player in the joint venture, BMW made it part of the contract that the Z4 would be released first, Toyota likely had little flexibility on release timing.
While it may not be good news, it makes sense from a marketing standpoint that there would be a long break between the concept and production unveiling. Why spend a fortune doing a prototype if it is going to be overshadowed by the release of the production car a few weeks later? The prototype...
1496 kg is a very porky 3298 lbs. That better be wrong unless it's cheaper than expected. Even the stated minimum (1388/3060) is not great, more than a base Cayman.
Looks very impressive, but then many otherwise meh cars do when they have highly modified racing bodies. But I do think this is a promising precursor. Vague on the release date though.