Amtrak's early years are often called the Rainbow Era which refers to the ad hoc arrangement of the rolling stock and locomotives from a pool of equipment acquired by Amtrak at its formation, that consisted of a large mix of paint schemes from their former owners. This rolling stock, which for the most part still bore the pre-Amtrak colors and logos, formed the multi-colored consists of early Amtrak trains. By mid-1971, Amtrak began purchasing some of the equipment it had leased, including 286 second-hand locomotives (of the EMD E and F types), 30 GG1 electric locomotives and 1,290 passenger cars, and continued leasing even more motive power. By 1975, the official Amtrak color scheme was painted on most Amtrak equipment and newly purchased locomotives and rolling stock began appearing. 
Turboliners arrived on the Detroit run on April 10, 1975. Additional equipment allowed Amtrak to add a round-trip in late April; the arrival of a third trainset in May made Chicago–Detroit the "first all-turbine-powered route". After one year of operation, ridership on the corridor had increased by 72 percent. The fixed capacity of 292 passengers on an RTL trainset proved an impediment; Amtrak could not add capacity when demand outstripped supply. Amtrak replaced one of the trainsets with a conventional locomotive hauling then-new Amfleet coaches in 1976; Turboliner service ended altogether by 1981 as more Amfleet equipment became available.