People sitting in a vehicle.
Five people sitting.
The sentence tells us that people are sitting, it doesn't give us a number so there is no way to imply that there are five people.
exists e1 x1 x2 x3.(a_topic(x1) & in(e1,x3) & n_vehicle(x3) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_people(x1))
exists e1 x1 x2.(a_topic(x1) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_people(x1) & card_eq_5(x1))