If you have booked a car, open it by briefly holding your caruso customer card/climate ticket against the blue/grey card reader on the windshield. A green light appears on the card reader and a short signal is heard, the car unlocks.
Alternatively, you can also unlock the car with the caruso carsharing app -> "Start reservation". However, we recommend that you always have your caruso customer card with you in case you are in an underground parking garage or somewhere with poor reception.