You do not waste the gas in your car to charge your cell phone. The car has only two functions after a hurricane:
To get food and medicine.
To get out of the area.
I live in an area that has fairly frequent power outage due to storms, sometimes even hurricanes make it inland this far. I've had the roof blown off my house before due to a hurricane. If you have no other means of charging the thing, yes you certainly do use your car charger to power up your cell phone.
If the roads are clear enough to even get out of your neighborhood, if they're clear enough get groceries or medicine, then they're clear enough to do a heck of a lot of things like going to find gas. Might be quite a drive, but still. And if you've got vehicles sitting in your drive that are low on gas in the aftermath of a hurricane, somebody's either not paying attention or pretty dumb. That's the only fuel storage a lot of people have, the gas tanks of their cars.