>>53193
Part 107 pilot here, no you almost certainly cannot fly a drone while driving, k e k. However, it can be autonomous or piloted by another passenger.
Also, drones over roadways is considered bad form.
As for the utility of a car equipped with a drone, as seen in Bladerunner 2049 - security vehicles with large patrol zones, off-road vehicles that need to see ahead where typical traffic updates do not work. And of course video producers or inspectors essentially turning a car into a rolling drone control OP has it's uses for mobile site work.
There are a few uses for it; car makers will probably avoid making this an already included feature because liability… so your only hopes of prototyping it are aftermarket.