The Oils-Energy group has plenty of great stocks, but investors should always be looking for companies that are outperforming their peers. Marathon Petroleum (MPC) is a stock that can certainly grab the attention of many investors, but do its recent returns compare favorably to the sector as a whole? By taking a look at the stock's year-to-date performance in comparison to its Oils-Energy peers, we might be able to answer that question.Marathon Petroleum is one of 249 individual stocks in the Oils-Energy se ...