Anyone who claims that all fast foods are the same must have brain freeze from slurping a chocolate shake too quickly. The most unique entrant that I have seen for some time in the fast food arena is Sonic (NASDAQ:SONC); the company's throwback drive-in concept is supported by its creative and unique menu items.

Sonic's line of "Toaster Sandwiches" features a bacon cheddar variety stacked with a hamburger, bacon, dill pickle, onion, lettuce, tomato, smoky cheddar cheese, an onion ring, and hickory BBQ sauce (hungry yet?). On its morning menu, the company has items such as "Breakfast Toaster Sandwiches" and "Pancake on a Stick." Sonic and Yum! Brands' (NYSE:YUM) Taco Bell (KFC and Pizza Hut, too) definitely put out different offerings than competitors McDonald's (NYSE:MCD), Wendy's (NYSE:WEN), and Checker's (NASDAQ:CHKR), which opt for more traditional burger and fries.

The key to Sonic's success has been differentiation, but it has recently reaped the benefits of extended hours of operations. The company's sales advanced 19% and its same-store sales grew 8.8% in the fourth quarter, well ahead of the 2% to 4% range expected and the largest increase over the past five years. Sonic's management expects revenues to increase 13% to 15% in the first quarter of fiscal 2005, with systemwide same-store sales coming in 2% to 4% higher.

Sonic's earnings rose 17% in the quarter to $0.33 per share, a penny ahead of the consensus estimate and $0.05 better than last year's figure. CEO Clifford Hudson summed up this success by saying that, "Sonic's solid sales momentum more than offset higher food and packaging costs." Looking ahead, the company sees earnings of $0.24 to $0.25 per share in the first quarter, a 17% to 19% increase over last year's earnings per share.

The company's extended hours led to an increase in labor costs, but the change also jump-started sales, led to reduced employee turnover, and increased customer satisfaction scores. Sonic also intends to nearly double its cable television advertising spending budget to $60 million in fiscal 2005 to support new product offerings and other sales initiatives.

If you're looking to invest in a double-digit sales and earnings grower with fresh ideas, Sonic would be a solid choice. A glance at the earnings growth outlook for the fast-food restaurants reveals that it's way ahead of the competition: Sonic, 18%; Checker's, 15%; Wendy's, 13%; Yum! Brands, 12%; and McDonald's, 8%. Sonic shares also trade in line with the industry's P/E to growth rate (PEG ratio) of approximately 1.15, which tells me that the shares still have some room to grow.

Stack up your own favorites ingredients between two pieces of bread, grab some pop, and dine on these views:

Fool contributor Phil Wohl spent more than 12 years on Wall Street and leaves fast food eating to the "cooking challenged." He does not own shares of any of the companies mentioned.