'69 monte carlo with full interior filtered ventilation, honey combed body armor, and enough horsepower to get you to the moon.
its really a better urban bug out vehicle then it is an environmental one... its a car that wont have you thinking "now that car has muscle. man, that thing could blow my car away". and likewise isnt the sturdiest looking car out there (ala the new yorkers and some of the late 70-early 80's caddilacs). but it has a lot of room for add on and improvements.
the basic idea being that of a getaway car. (taken from andrew vachss' getaway driver book)
"what if they make a blockade?"
"i'll drive you out."
"what if they have snipers?"
"i'll drive you out."
"what if we're out numbered?"
"i'll drive you out."
try to find a car that can acheive that, and you have an excellent urban bug out vehicle...
must be able to take bullets to the windows without a)spidering beyond visibility - or, have an internal camera mount for driving when there is no visibility - or, your have to have enough skill with your car to be able to drive in near 0 visibility.
must be able to drive through road blocks, including cars and other boudaries, such as road islands islands or road debris.
must be able to accelerate with a lot of torch, incase you are boxed in.
must be able to ventilate out tear gas and smoke.
must have a fire retardant outer shell and passanger compartment
must have crash reinforcments on side panels, front and rear to protect main driving components.
must be able to withstand multiple crashes without major driving impediments
must have a large enough fuel cell to do all of the above for a semi prolonged period of time (3-4 hours, over several days time, enough to get you out of the city when the entire city is against you)
road warrior style

the monte carlo is a decent option for all of the above, because of its ability to be modified while having a huge engine, and large trunk compartment, and good manueverablity...
given all the requirements above, it would actually make an okay vehicle for the hills, as long as you could raise the suspention enough.certainly wouldnt be ideal for that application though.