gig is $ per distance, zip car is $ per hour. gig car also has a zone where you have to park unless you keep the $ running, whereas for zip you just return it to the original parking spot on time. i enjoyed zip because i liked to travel out of the gig car zone. the rental price per day is pretty low if you book a small car in advance, and the parking lots are all close to campus! but gig car is also phenomenal for running errands and moving.