UCSD - I almost always get gas at Shell.. My car actually gets 6-7 MPG better milage with their gas. I'm usually 24-26 with other gas stations (never above 27) and 31-32 with Shell (I've gotten 33, 34 a few times - but never under 30). Also, Shell gas always lasts me a full 7 days, whereas other I have to refill at 6 days... I've done numerous calculations between their gas and the other stations around here... The only time I get gas elsewhere is if there is not a Shell around or if I'm about to run out and I'm next to another station.. and it always turns out for the worse
Yes I'm a geek who sits there calculating after every re-fill

So I may pay the extra 1.00 per tank, but I'm getting an extra 60 miles or so for that dollar. I also love that every other gas station always has a line and at Shell you can just drive up and get it. Very convenient. (Most probably because it costs more so people stay away - haha)