But why does Tesla need a halo car? They already have the consumers’ attention. Lots of people would buy Teslas today but can’t because Tesla is unable to mass produce the Model 3.
I doubt they'd allow that judging by what happened the last time they were featured.
The team at the Grand Tour are going to have to get used electric cars, since I expect all the fastest cars will be electric from this point. If they can't get a loaner car, they'll borrow or buy one, they've done that before.
Product design / R&D is also different resource pool to manufacturing (well, at least in my mind it is). Manufacturing issues may have forced redesigns but they'll need to keep working on the next thing; competition certainly won't stand still.