"Passenger room" refers to the amount of space available inside a vehicle for the people who are traveling in it. It describes how much room or space there is for the passengers to sit comfortably and move around. Full definition
Anyone caring for a family will tell you that a vehicle should have plenty of passenger room and cargo space while still offering a durable interior and quality safety features. (glendaledodgeblog.com)
In the 1930s, trying to create more passenger room in the front seat, automakers took the stick shift off the floor and put it on the steering column. (articles.orlandosentinel.com)
Great mileage, comfortable driver seat and ample passenger room in the back. (autolist.com)