We do car bar when we want to save money. Usually involves parking on the street and downing a couple of brews (always out of a glass, never the bottle) before going someplace. Usually we bring along peanut butter and jelly sandwiches so we don't have to buy food out, or we'll split an entree or something instead of buying two.
I have a couple car bar experiences that were lots of fun. We were doing a trip I think it was 2008 when the Badgers had clinched a share of the basketball Big Ten title and had one final game at Northwestern to win the title outright on my birthday, no less. My buddy kept wondering and worrying about where we were going to drink before the game because he was having a hard time finding a bar within walking distance, and I would ease his fears by reassuring him that in case of need, there was a bar in my car. We wandered around for a while and tried to find some place to get a drink, said fuck it and chilled out of the car for an hour drinking while parked on the street. I think there were four of us that day. The Badgers won.
Another great one was enjoying some Central Waters Mud Puppy Porter while parked in front of the Old Faithful Inn at Yellowstone, trying to get a round in me before visiting the bar at the Inn. We were camping for two weeks (one night in a hotel in the middle to break up the trip, but otherwise sleeping outside every night) and so every comfort such as visiting the bar was very much appreciated, even more so when you already got a beer in ya.