Like the title of the post asks, how far can you go? Right now I can go about 230 miles. What do I mean? I'll tell you. I always run off of the top half of my fuel tank.
If some sort of disaster were to happen in your area tonight, would you have enough fuel to get anywhere? If that disaster affected the power lines, chances are any gas stations in the area would be dead in the water. But even if they did work, how long would the lines be? If you had a half tank or better already in your car you would be able to get somewhere, anywhere other than where you are right now.
I remember 9/11, when we were attacked by a bunch of scumbag muslims, one of the first things I thought about was what if we had to move to another area. At that time we still lived in town. There was a gas station right across the street. The first thing I noticed was that they had raised their prices to more than double the going rate and second, there was a line about a half mile long waiting to get gas. This station and several others in the area were later sued by the attorney general for price gouging and had to give refunds to the customers that purchased fuel.
Running off of the top half of the tank can be a pain, I know that. But think of the consequences of having a quarter tank and no way to fill up if you were suddenly required to evacuate. It has been a battle to get my Bride to get on the program. She backslides occasionally, but hers is the vehicle we would need most in an emergency, that or the monster Suburban, which, by the way, has three quarters of a tank (and the tank is 40 gallons!) even as we speak.
I also have three five gallon gas cans in the garage that I keep full at all times. This is the lawnmower supply, but it also makes a good emergency stash too.
You probably have a bug out bag (you do, right?) and a hell of a good plan, but without enough fuel, your plan and your gear aren't worth having...