 In 1946 GM began offering its Thermo-matic heating and ventilation system, and in 1952 started making suburban models (identifiable by larger passenger windows, and equipped with high-backed forward-facing seats and optional luggage racks).Beginning in 1953, air-ride suspension became standard on all but the smallest model buses, and in 1958, air conditioning was added as an available option.In 1959, GM introduced its New-Look bus with the "fishbowl" style front window, and production stopped on all "old-look" buses other than the "second-generation" models