It's a gas station.
But it has a car wash. For my lazy ass who doesn't want to wash my car by hand, I like stations like this and there's one near my parent's place. Which means, when I visit, I can fill up and wash the bug guts and dust off my ride.
As for the convenience store, I wouldn't know. I haven't set foot in there in all the years this place has been around.
I fill up. Drive thru the wash. And leave.