Seriously, your car is often extremely important both before, during, and after a storm. It is likely to be how you get to your boat in the first place, assuming you aren't living aboard. It may be your escape hatch if the storm proves to be too threatening or if the worst occurs and your boat is damaged, aground, or possibly sunk. Third, once the storm has passed your car may be the only means to escape the damaged area, and it will likely be your lifeline to obtain food, water, and repair materials.
Keep the car filled with gasoline, if possible, and consider storing some spare water and supplies there. My trunk always has things like jumper cables and even a small starter battery that doubles as a cell phone charger. Being able to escape a wet, damaged boat and possibly even spend a night in a dry car with a charged cell phone might look pretty good after a storm. You may even consider storing some important valuables in the car, if you can find a great spot to leave it.
The other day I heard a great tip while watching a weatherman talking about the flooding during Hurricane Harvey in Houston. He said check out your height above sea level by using the compass app on your iPhone. My Android phone doesn't come with a native compass app, but there are many in the Play Store and quite a few do include height above sea level. I'm still researching which ones are good and which ones prove to be accurate, but this can be an extremely valuable piece of information to have when thinking about where to put your car. Protection from wind and debris will mean nothing if the car is flooded--seek higher ground!
This often means abandoning the marina parking lot, which is frequently located strategically right next to the docks and the harbor--not the place to avoid damaging storm surges that come with hurricanes. In New England, one can often walk inland a couple of blocks and you'll notice that you are going uphill. Florida, not so much. In fact, it may not be possible to find a place immune to tropical storm flooding within a reasonable distance from the marina. If that is the case, consider parking garages that allow you to go up a floor or two. These tend to be strongly built structures which may also provide shelter from the wind, and more importantly flying debris.
Until you have experienced a hurricane or two it is hard to appreciate the dangers of debris flying through the air. Maybe you have noticed that people cover large building windows with plywood sheets. Think of your car windows enduring the same pummeling. However, don't even think about trying to cover your car with any sort of normal cover. It will either shred in the storm, and/or flap so much the car's paint will be ruined--probably both.
I actually search for parking opportunities that allow me to either point the car into the wind or go stern (rear bumper) to, and downwind of a large, sturdy structure made of concrete. If you park close to such a structure, with the nose of the car up towards a wall, it can prevent rain from driving into the engine compartment under the force of 100 mph winds, and anything that is blowing through the air will be blocked.
Believe it or not, these types of parking opportunities are something I note during the boating season. Where can I park the car, nearish my boat, with protection from likely storm force winds, high enough above sea level to be safe from flooding, and also a place that the car can be left without fear of being towed or broken into? It can be tough to find such a place, so start making mental notes as you explore the area near a new marina or mooring.