IR has several classes of travel, with or without air-conditioning. A train may have one or several classes. Slow passenger trains have only unreserved seating, and the Rajdhani Express, Shatabdi Express, Garib Rath Express, Double Decker Express, Tejas Express, Humsafar Express, Duronto Express, Yuva Express, and Vande Bharat Express have only air-conditioned classes. Fares for all classes differ, and unreserved seating is the least expensive. Fares for the Rajdhani, Duronto Shatabdi and Vande Bharat Express trains include food. In September 2016, IR introduced dynamic fares for the Rajdhani, Duronto and Shatabdi trains (except 1AC and EC classes) to increase revenue. Long-distance trains usually include a pantry car, and food is served at the passengers' berth or seat. Luxury trains (such as Palace on Wheels) have separate dining cars, but these trains cost as much as—or more than—a five-star hotel room.