this post on reddit speculated there was a new vehicle being tested on the track last night after dark. Not the semi. And sounds different enough in shape to not be the Y. Maybe the Pickup is the Semi Truck reveal "something else".
I have seen many model 3's s's and X's being tested in the track at the Fremont factory. Today at around 9:30pm I saw the back lights of a different car it seemed to have Tesla styling but it definitely is not one of the 3 models we have already seen. The sizing and light placement makes me think it could have been a pickup truck but it was too dark to make out anything other than the lights of the car. Not much info I know but I thought y'all might like to know. This is a Monday at 9:30pm so mayebe someone else could look around that time next week if I don't. I used to see model 3s regularly on certain days of the week so I would think a new car would have some regular testing times.