Detailed Instructions: Given a travel related situation, and given a specific question about the situation, summarize the question into a title
Q: I'm doing a house swap with another family, and as part of the logistics, at a certain point I have to leave my car for them, and they will pick it up a few days later. This happens to be in Newark, NJ, but the problem is pretty general.

We can't meet in advance to exchange keys, and I don't have a third party who could hold the key.

Can anyone suggest a way to accomplish this?

A:
How can I leave a car for someone if we can't meet in person?