In the 1910s, small sheds were constructed to hold lubricating oils, greases, and equipment. Often the roof projected outward, supported by posts, to provide a small covered area for a car to pull in. These early buildings were precursors to the drive-in filling stations that fully developed in the late 1910s and 1920s.
The image below illustrates a typical shed style gas station with roof overhang. Notice the simple, practical design of the structure.