Was it actually cheaper than Ubering? I always felt that the price was very similar and Ubering removed the need to be the driver. Only ever used Car2Go when I actually needed the car space.
From the airport it's a lot cheaper: on an evening return from the airport (no traffic) it would be $20 for a 30 minute car2go trip to N Seattle vs. $40+ for a (non-shared) Lyft.
Plus no risk of getting speeding/parking tickets, and if you are in an accident no insurance hassle to worry about (I assume the car sharing services have some sort of excess if you get into an accident).