Sure the tacos are great, particularly as they include an amazing fixings bar, but you're missing some amazing dishes if you ignore the pozole, a hominy stew, and the sincros, which are like quessadilla, but with refried beans.
A friend of mine updated his Facebook status to say that he had just driven 50 miles to eat at his favorite gas station taco stand. It drew 40 comments from people on his friends (including me) list exclaiming that they, too, had a favorite gas station taco stand and had either eaten there recently or were suddenly overtaken by a powerful urge to go back. Then we all realized we were talking about the same gas station taco stand: Taco Bar, tucked into the Washingtonian Gas station right of Exit 9 on 270. I freaking LOVE this place. Not just because it is apparently as well-kept a secret as Samantha's in Silver Spring was circa 2008, but because I TOTALLY found it first. :)