You’ll need to check your car insurance policy to see if it offers cover for you to drive someone else’s car. If it does, it might only offer third party cover, which will cover you for damage to another car or injuries to other people. You won’t be covered for damage to the car you’re using, or your own injuries, if the accident is your fault.
You have the option to get temporary car insurance for a third party car (Zusatzpolice Kfz-Versicherung) through another car insurer. Please contact your insurer directly, Joonko does not offer any temporary coverage.