I had a close friend ask me this a couple months ago.
She said "How would you like to make some money by renting me your car for my vacation? I'm going skiing with my kids and all that equipment won't fit in my cart" (I have an Outback) . I was kind of stunned, this friend is a terrible driver- hit an old man's car 6 months ago, then got a ticket 3 months ago. I used my spouse as a reason to say no - "he's really picky about who drives our cars, I don't think he'll say yes. Why don't you rent one?" I think she just drove her own in the end.