Fast food drive-thru

Here is a scenario involving the many drive-thru's that we frequent on a daily basis. I went for a drive with my older son tonight for some father and son time (I went to work today). My son said that he would like to have Mcdonalds and I said why not. I'll just get a coffee coolata while I'm there. I drive up the the fast food joint and saw that it was full inside and decided that the drive-thru would be a little faster. So there I was after ordering, stuck between two cars and in a single lane with no way of getting out if I wanted to. This single lane had me between the the wall on one side and a hedge on the other. This is when it occurred to me that this is a perfect place to get robbed or carjacked because I had no outlet until the car in front of me moved.

How would you handle a situation where two perps come to your driver side window and passenger window and they are armed with guns. I never drive with my doors unlocked and my windows are always rolled up. Upon seeing a gun would you shoot through your own window at the robbers when you have a chance or would you just not go to the drive-thru anymore. There was a case in West Palm Beach at a Wendys where this guy shot a few people and killed a firefighter then took his own life. So it's not that much safer inside these places either. What do you do? Once you start carrying it's amazing how you don't stop thinking about your surroundings. I would appreciate any feedback whether good or bad. thanks.