If it´s a suggestion, I´ll give my .2 euros.
1) Flat color: grey, green, dark blue, or some other "don´t look at me, I´m not even here" color
2) roof rack or box, only to use it in extreme need.
3) Not luxury, but a spartan interior: hand crank windows, leather seats, and alike. Maintenance issues.
4) forget alloy wheels, mud tires (just if you think you could have to go off road to avoid a potentially dangerous situation)
5) Radio (the choice is yours, go to the commo threads)
6) automatic transmission - A kid, woman, or an elder can drive it, and you could if your left ankle broke or got a shot, or...whatever, you got the idea.
7) Depending on your area, and the conditions of the road to your retreat: 4x4.
8) Brand? Toy, Mitsu or Nissan. I´m overcoming anything with Detroit scents on it.
9) Buy SUV before a Minivan. Off road behavior is QUITE different.
10) dark Tinted windows (avoid a super duper stereo, please. You are surviving in an urban environment)
11) Front (perhaps even rear) guards in case of a gang in a car next, or in front of you, trying to block.
12) A MEDIUM, powerful enough engine. Just in case you have to ride over an smaller car with some UZIs and pistols non friendly holders. Should be fun. If you have the chance to do it and survive, please send some pictures later.
13) Diesel if speed is not that important to you. You could convert it later, if things really gets fanned, to work with WVO. And are MUCH reliable than some gas engines out there. issues?...mm..noisy and smelly.
14) don´t get anything with stickers (or just peel it off), even if they´re pretty funny. If a police or soldier notes it, and funny enough, their will keep it in their minds and could go to surface in the less adequate moment.