The cars were supposed to be locked
According to all that steam in the car, Jack and Rose enter one of the Titanic’s cars and have their way with each other in a famous love scene. However, how in the world would the two get one of the cars open?
In real life, the ship did have cars, but they were locked. Strangely enough, it seems that they didn’t want a few outsiders to get into their cars and taint them. As they say, they were going to have to get a room unless Jack was skilled at car hijacking.