More and more cars are supporting this, so I wondered how you could let someone else drive your car without giving up your phone. At least one car, the Kia Niro EV, lets you delegate with a text message. The Hyundai version says, "
you can share car keys for a limited time or allow only certain features. For example, it is possible to send a delivery man your digital key that can only open the trunk so that he/she can put the package in it, or lend a car to your friend for only a limited time."
These sound like capabilities to me, but I haven't been able to find any details.