Yellow Coach developed distinctive streamlined models which introduced a high floor, underfloor luggage storage, a flat front, air conditioning, and a diesel engine, supplying more than 1,250 buses during Greyhounds' years of fastest growth. GM purchased the company outright in 1943, merging it into their GM Truck Division to form GM Truck & Coach Division. Although GM continued with the Yellow Coach T-series and P-series product lines, the Yellow Coach badge gave way to the GM Coach or just GM nameplate in 1944. Widespread production of Yellow Coach designs—including certain ZIS buses produced in the Soviet Union—continued until 1959. Limited production of the two remaining small-capacity "Old Look" models (3101/3102 and 3501/3502) would continue until 1969. GMC badges did not appear until 1968. Car rental - Hertz Drivurself Corp/Yellow Drive-It-Yourself The company owned a subsidiary, known as either Hertz 'Drivurself Corp' or 'Yellow Drive-It-Yourself' which was sold with Yellow Coach to General Motors and eventual purchased back by Hertz in 1953 with The Omnibus Corporation which was then renamed The Hertz Corporation the following year. Models produced Letter series (1923–1936) Yellow started its model designation at the end of the alphabet and worked forward. Initially four types were offered: Z type single-deck bus or coach Z type double-deck bus Y type coach X type bus or coach. All were conventional front-engine design vehicles powered by Yellow Knight I4 sleeve-valve gasoline engines, or a General Electric gas-electric hybrid unless noted otherwise. The Knight engine was connected to the rear wheels by a mechanical drive shaft. In gas-electric models, a gasoline engine in front supplied electric power to two large electric motors mounted on the rear axle. 700-series (1931–1939) In 1931, Yellow Coach introduced its 700 series buses, featuring one of the first bus designs to mount the engine in the rear. Mounting the engine in the rear represented a significant innovation, reducing mechanical losses, noise, and weight of a long drive shaft and exhaust running between a front engine and the rear drive and tailpipe. Bus manufacturers in Germany and the United Kingdom would not perfect rear-engine models until the 1950s. Customers did not always prefer rear-engined designs, noting that front engines were easier to access, and placed engine noise and vibration away from passengers and sometimes outside the coach body. Eventually, the 700 series included both front- and rear-engined models. In 1934, Dwight Austin, patent-holder on an innovative rear-drive system,