Investors focused on the Oils-Energy space have likely heard of Sunoco (SUN), but is the stock performing well in comparison to the rest of its sector peers? Let's take a closer look at the stock's year-to-date performance to find out.Sunoco is one of 253 individual stocks in the Oils-Energy sector. Collectively, these companies sit at #8 in the Zacks Sector Rank. The Zacks Sector Rank gauges the strength of our 16 individual sector groups by measuring the average Zacks Rank of the individual stocks within the groups.The Zacks Rank is a proven system that emphasizes earnings estimates and estimate revisions, highlighting a variety of stocks that are displaying the right characteristics to beat the market over the next one to three months. SUN is currently sporting a Zacks Rank of #2 (Buy).Over the past three months, the Zacks Consensus Estimate for SUN's full-year earnings has moved 6.97% higher. This shows that analyst sentiment has improved and the company's earnings outlook is stronger.Based on the most recent data, SUN has returned 12.34% so far this year. Meanwhile, stocks in the Oils-Energy group have gained about 11.19% on average. This means that Sunoco is performing better than its sector in terms of year-to-date returns.Looking more specifically, SUN belongs to the Oil and Gas - Refining and Marketing - Master Limited Partnerships industry, which includes 12 individual stocks and currently sits at #238 in the Zacks Industry Rank. This group has gained an average of 13.77% so far this year, so SUN is slightly underperforming its industry in this area.Investors with an interest in Oils-Energy stocks should continue to track SUN. The stock will be looking to continue its solid performance.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Sunoco LP (SUN): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research