A "casting call" has been put out, asking for time-period cars for using in the backgrounds of scenes - late 1970s to early 1980s cars, but specifically ones that are not coloured yellow, red, white or black. This might be to make sure that they don't clash with the "robot" cars in the shot, but that seems a little strange, it's not as if people are going to see yellow cars in the background and assume one is Bumblebee.
This has led to speculation that the leaked photo of four cars of those four colours, could be actual movie (robot) cars, but we'll have to wait a while to see if that was true.

The shooting schedule is said to go from July 31st to November 15th, which is three and a half months. I think that's about the right amount of time for a smaller budget movie that isn't travelling around the world, and it gives them about 6 months in editing/post-production, to make sure it gets approval from test audiences.

And one of the producers, Lorenzo Di Bonaventura, has confirmed that filming is starting in a weeks time... and amusingly notes that since it is set in the 1980s, it won't be burdened by what happened in the 5 Michael Bay movies. He mustn't have been taking much of a lead role as producer, or couldn't follow the movies either, or else he would know that every single one of those five previous movies involved significant events that took place well before the 1980s. And each of those significant historical events can't be ignored in a 1980s movie or else there will be more contradictions that viewers will be too busy trying to process, to be able to enjoy it.