The Berlin-based car-sharing platform carzapp enables people to rent their cars to others at the spur of the moment, without having to hand over the key, and with no risks. Thanks to the novel ZappKit hardware, the temporary driver can open the car using a special smartphone app. Car owners and renters communicate via a website. The owners decide themselves when to rent their car or transport vehicle, to whom, and at what price. The climate idea behind the new technology: Private cars can be used more efficiently and fewer new cars need to be manufactured, reducing the amount of carbon dioxide arising from automobile production in the medium term.