Surely the cost of renting a car is far, far higher than the depreciation on a car caused by driving the same distance?
Let's take a drive I did recently: Minneapolis to Boise. Twenty-ish hour drive; if you have a couple of drivers, you could maybe get it done in one day. Let's budget two days for car rental. Pick up, drive, stay over night, drive, drop off. Hertz is quoting me between $100 - $150/day depending on car size. Let's say 2 days @ $150 = $300. According to a random internet article [0], the cost of driving (minus gas -- which we're spending either way, though maybe in different quantities) is $0.16/mile (yes, includes maintenance -- forgot to mention earlier). Boise is 1450 miles away from Minneapolis @ $0.17/mile = $232. Yeah, a little more expensive; Hertz needs to break even after all. But not by as much as one might think. And for three passengers, much less than a short-notice flight.
[0]: https://www.mymoneydesign.com/what-is-the-real-cost-of-drivi...
If you've ever been stuck in foreign garage waiting for your car to be repaired you'll appreciate the convenience of having a national network of replacement cars at the ready.
With Hertz & friends, easy to rent a van, take it some where and either leave it there (and fly home) or drive back. It'd probably be a wash when milage depreciation is thrown in?
And driving with a cello is a lot better than flying... :-)