Generating 4-5 miles a day is peanuts ... but if I said vampire drain was 4-5 miles a day, people would be apoplectic, right ?
This shows that most people's opinions are a waste of good bandwidth but the kernel of truth here is that it is context dependent. The story starts with cost and ends with alternative charging. If I want to go camping off-grid for a couple of weeks then car roof PV (presuming it is not shaded) is awesome. On the flip side, if the car roof PV is competing with home PV I can install for under $1 a watt, then it is a hard pass.
For *me*, I would not buy it for a car but if it was not too expensive I would think about it on a cybertruck.