If you already have a Honda Fit, try to equip it with GHB ... etc. as much as you can, because that is what you have. However, if "survival vehicle" is something that comes in your dreams and you are thinking yet to buy a car, try something a bit better.

As some have mentioned, you may have to run over curbs. This will not only require higher ground clearance, but sturdier body and suspension.

I have a new Toyota Camry. Although bigger than the Honda Fit, I am NOT happy with its low ground clearance because our roads are not that great. So, what happens if there is some kind of SHTF and roads are full of debris !!! Or if I had to take a dirt road !

Having said that, I am considering a sub-compact 2-3 years from now, when I retire and want a small car to drive around town. Better maneuvering in crowded streets and parkings, and maintenece is cheaper. It all depends on your priorities.