This burgeoning burger chain is the worst-kept secret in the markets where it's succeeding, but it hasn't cooked into a household name. That's where a Super Bowl ad would come in handy. Without one -- or really any advertising, for that matter -- the chain built on big burgers, fresh ingredients and free peanuts grew from a local Washington, D.C., outfit back in 2002 to more than 900 locations in 46 states and Canada today. Another 1,500 are in development as sales grew more than 37%, to $625 million between 2010 and 2011. Fast-casual chains such as Panera Bread ( PNRA) and Chipotle ( CMG) don't get a whole lot of commercial play as it is, but fast-casual burgers have been booming. Fast-casual burger joints including Five Guys and In-N-Out Burgers saw sales grow 17% by the end of 2010 while fast-food burger sales put up modest 1.6% growth during the same period. As Burger King considers delivery, Wendy's ( WEN) becomes more burger-centric as it eyes the No. 2 spot in the U.S. and McDonald's ( MCD) grows by building beyond the burger, now is as a good a time as any for fast-casual and Five Guys to seize the spotlight. But that's just not going to happen. Five Guys and its cohorts have come this far by sticking to the formula and plowing profits back into the product instead of spending millions on marketing. That $3.5 million can go toward better beef, plumper pickles or pallets of regional potatoes. A Super Bowl ad could make Five Guys the next big thing in burgers, but you get the feeling it wants something better.