I understand not wanting to crowd and think it’s perfectly reasonable to only take 3 passengers. However, being that there is a functional fourth passenger seat, I think it’s disingenuous to use the term “full car” in that situation.
As far as the crowding itself– ask the passengers! I personally think the convenience of the ride outweighs the discomfort of being squished, and although I’m tall for a woman, I don’t mind being the one to take the middle seat. I do know, however, that other people feel differently.