What transportation with gull-wing doors was used in the Back to the Future franchise?
DeLorean time machine:  In the feature film series, Dr. Emmett Brown builds a time machine based on a DeLorean DMC-12 car, to gain insights into history and the future. DeLorean DMC-12:  The car features gull-wing doors and an innovative fiberglass body structure with a steel backbone chassis, along with external brushed stainless steel body panels.
DeLorean DMC-12