Years after the fast-food chain began advertising in the Philadelphia region, our first Sonic has opened. (Expect more in the coming year.) The Sonic gimmick is drive-in-style service, a concept that seems less than novel now, when eating in your car is an everyday American activity. It doesn’t get more convenient than this, though: your own drive-up menu and intercom, complete with credit-card swipe. While there are no waitresses on roller skates to deliver the solid quick-serve burger, super-carbonated customized soft drinks and sadly bland onion rings to your car window, there is a condiment girl, hawking packets of honey mustard like they’re packs of Marlboros.