What's the reason Yuta wanted them to sit in the car?

I think its because of the camera

He probably wants to get everything on cam for evidence purposes, that way seunghyun can't back down later

Thank you. Thought it was a trap or something to blackmail him with

But yes now it can be too, because seunghyun lost it and probably they will have sex on the next chapter. He shoot himself on the foot there by going crazy on yuta now yuta will have some juicy footage to make him behave later if needed