I agree with the rest - when it's good it's good but when something happens it goes horribly. Read your terms and conditions people!
Whenever you park at the car2go stalls at the airport you get charged an extra 12.50 + tax on top of your trip total - I was expecting the trip to automatically end as it was counting down from 15 to about 6 when I ran to catch the shuttle to the car - but then halfway through my check in I got a text saying the trip didn't end properly. I then had to take a taxi (approx same cost of the car2go rental) to book it back to the car to end the trip by scanning my card without having to do anything else like shut the door/window, etc. Still caught my flight but the trip not ending definitely created unnecessary grief.