Leased vehicle question.

My niece (26) needs a car to take a trip from Chicago down to Nashville. Her car sucks at highway speeds and is a gas hog.

I suggested she take my Ioniq 5 XRT. My wife thinks it's a bad idea because it's a lease. The car is insured, she's got her own insurance, and I can add her as a driver on my insurance policy. Is there anything that I don't know about that I need to worry about?