2013 has been a stellar year for shares of O'Reilly Automotive ( ORLY); shares of the $13 billion auto parts retailer have rallied more than 30.7% since the start of the year. That's almost twice what the S&P has been able to do over the same time period -- quite a feat. >>5 Stocks Insiders Are Scooping Up O'Reilly is the second-largest auto parts chain in the U.S., sporting a network of more than 4,000 stores. While ORLY started off primarily serving the commercial auto parts market, the acquisition of CSK Auto shifted the firm's mix more to the retail side. That's important positioning: as other auto retailers clamor for commercial business by adding "stores within a store" to their existing locations, O'Reilly already owns an established network of parts suppliers for independent shops. The auto parts industry has enjoyed some help from the broad economy in recent years -- the biggest is the age of the average car on the road today. Despite the uptick in new car sales, the average age fleet age in the U.S. is higher than ever before. As consumer look to prolong the lives of their vehicles, O'Reilly shareholders stand to profit. With rising analyst sentiment in shares, we're betting on ORLY this week. To see all of this week's Rocket Stocks in action, check out the Rocket Stocks portfolio at Stockpickr. -- Written by Jonas Elmerraji in Baltimore.