Tsar, if your hometown is currently a couple hour drive away, even slower going on back roads should be able to get you there on a single tank of gas. The trick then is to get in the habit of filling the tank often, at a minimum filling it when it gets down to half but I’d suggest filling it when it gets down to 3/4’s. Once in the habit, doing this won’t seem odd at all. If the friend who owns the car however doesn’t see the same threats that you do, convincing him of the wisdom of full gas tanks could be tough. Another thing is to start driving the alternative routes so as to familiarize yourself with them. Every time you go home, use a different route. Not knowing whether the region you live in is mountainous or forested, if it is, then having topo maps could come in handy if you needed to go offroad in order to get around a town or other obstacle.
The best solution of course is to head home before events hit the critical stage. A single day can make all the difference, sometimes even a few hours head start. You and your friends all need to be on the same page that when one of you says its time, its time and you head out.