Ah You’re right, the window design is also straight cross the bottom rather than curved. My new guess is a Honda Acty, which is only 6.3ft. Ill update the comments
And to be fair I upvoted your comment as I agreed it looked more like a 4.5ft bed. But then I looked it up.
I don’t really understand the comment about the Silvarado. Are you saying a silvarado has a bed longer than 6.5ft?