Exhibit 99.1

Marathon Petroleum Reports Second-Quarter 2012 Results

FINDLAY, Ohio, July 31, 2012 – Marathon Petroleum Corporation (NYSE: MPC) today reported second quarter net income of $814 million, or $2.38 per diluted share, compared with net income of $802 million, or $2.24 per diluted share, in the second quarter of 2011. For the second quarter of 2012, net income adjusted for special items was $867 million, or $2.53 per diluted share, compared with net income adjusted for special items of $819 million, or $2.29 per diluted share for the second quarter of 2011.

“Our operational flexibility and location of our assets enabled us to optimize operations and capture value from dynamic market conditions to produce strong earnings,” said MPC President and Chief Executive Officer Gary R. Heminger. “With our refining capacity balanced almost evenly between the Midwest and the U.S. Gulf Coast, we were able to take advantage of strong crack spreads and increasing production of Canadian and unconventional crudes. At the same time, Speedway achieved a 34 percent increase in segment income over the second quarter of 2011, due primarily to an increase in merchandise and refined product margins.”

Heminger also noted that MPC took an important strategic step on July 2 by filing a registration statement in anticipation of a proposed initial public offering of common units of MPLX LP, a master limited partnership. MPLX LP, a wholly owned subsidiary of MPC, was formed as MPC’s primary vehicle to own, operate, develop and acquire crude oil pipelines, hydrocarbon-based products pipelines and other midstream assets. An application is being made to list the common units on the New York Stock Exchange under the symbol “MPLX.”

Heminger also provided updates on other recent and ongoing MPC initiatives. “During the second quarter, Speedway completed the acquisition and integration of 87 GasAmerica locations. In mid-July, Speedway completed the acquisition and integration of 10 Road Ranger locations,” said Heminger. “Our Detroit Heavy Oil Upgrade Project also continues to be on budget and on schedule, and we expect it to be operational by year-end. This investment is intended to enhance margins by equipping the refinery to process lower cost feedstocks, including Canadian bitumen-type crudes.”

Commenting on the company’s recently completed $850 million accelerated share repurchase program, Heminger said it represented an important component of MPC’s ongoing plan to return capital to shareholders with $1.15 billion remaining under the current $2 billion share repurchase authorization. “We remain committed to maximizing total returns to our shareholders, and recognize the trust our investors have placed in us to exercise discipline in the allocation of capital,” he said. “We will continue to strike a balance between making value-enhancing investments in our business and returning capital to shareholders. Our recent decision to increase the quarterly dividend from 25 cents to 35 cents per share further underscores this commitment.”

Segment Results

Total income from operations was $1,307 million in the second quarter of 2012, compared with $1,325 million in the second quarter of 2011.

Refining & Marketing

Refining & Marketing segment income from operations was $1,325 million in the second quarter of 2012, compared with $1,260 million in the second quarter of 2011. The $65 million increase was principally the result of a higher Refining & Marketing gross margin, which increased to $11.13 per barrel in the second quarter of 2012 from $10.78 per barrel in the second quarter of 2011. The primary factor contributing to the increase in the gross margin was a higher Chicago and U.S. Gulf Coast LLS 6-3-2-1 blended crack spread, which increased to $8.46 per barrel in the second quarter of 2012 from $5.53 per barrel in the second quarter of 2011.

As of June 30, 2012, the Detroit Heavy Oil Upgrade Project was 96 percent complete and remains on budget and on schedule for expected construction completion in the third quarter of 2012. Immediately following, there will be a 70-day planned turnaround, with the upgraded refinery anticipated to be online by year-end.

Speedway

Speedway segment income from operations was $107 million in the second quarter of 2012, compared with $80 million in the second quarter of 2011. The $27 million increase was primarily the result of higher merchandise, gasoline and distillates gross margins, partially offset by an increase in operating expenses. Speedway gasoline and distillates gross margin per gallon averaged 16.39 cents in the second quarter of 2012, compared with 15.02 cents in the second quarter of 2011.

Speedway same-store merchandise sales increased 2.2 percent in the second quarter of 2012, compared with a 0.3 percent increase in the second quarter of 2011. Same-store gasoline sales volume increased 2.1 percent in the second quarter of 2012, compared with a decrease of 4.5 percent in the second quarter of 2011.

During the second quarter of 2012, Speedway completed the acquisition and integration of 87 GasAmerica locations throughout Indiana and Ohio. This acquisition supports MPC’s strategy to increase Speedway sales volumes and complements the company’s existing network of assets.

Pipeline Transportation

Pipeline Transportation segment income from operations was $50 million in the second quarter of 2012, compared with $54 million in the second quarter of 2011. The decrease was primarily due to a decrease in pipeline affiliate income.

Corporate and Special Items

Corporate and other unallocated expenses increased $23 million in the second quarter of 2012 compared with the second quarter of 2011. The increase primarily reflects the impact of being a stand-alone company in 2012 compared to expenses incurred prior to the June 30, 2011 spinoff. During the second quarter of 2012, we recorded pretax cumulative pension settlement expenses of $83 million resulting from the level of employee lump sum retirement distributions occurring in 2012. During the second quarter of 2011, state income tax legislative changes were enacted, primarily in Michigan, resulting in an adverse tax impact of $17 million.

Strong Financial Position and Liquidity

On June 30, 2012, the company had $1.9 billion in cash and cash equivalents, an unused $2 billion revolving credit agreement and a $1 billion unused trade receivables securitization facility. The company’s credit facilities and cash position should provide the company with sufficient flexibility to meet its day-to-day operational needs and continue its balanced approach to investing in the business and returning capital to shareholders. As of June 30, 2012, the company’s strong financial position was further reflected by its debt-to-total-capital ratio of 24 percent.

Conference Call

At 10 a.m. EDT today, MPC will hold a webcast and conference call to discuss the earnings release and provide an update on company operations. Interested parties may listen to the conference call on MPC’s website at http://www.marathonpetroleum.com by clicking on the “2012 Second-Quarter Financial Results” link. Replays of the conference call will be available on the company’s website through Thursday, August 16. Financial information, including the earnings release and other investor-related material, will also be available online prior to the webcast and conference call at http://ir.marathonpetroleum.com in the Quarterly Investor Packet.

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About Marathon Petroleum Corporation

MPC is the nation’s fifth-largest refiner, with a crude oil capacity of approximately 1.2 million barrels per calendar day in its six-refinery system. Marathon brand gasoline is sold through more than 5,000 independently owned retail outlets across 18 states. In addition, Speedway LLC, an MPC subsidiary, owns and operates the nation’s fourth largest convenience store chain, with approximately 1,460 convenience stores in seven states. MPC also owns, leases or has ownership interests in approximately 8,300 miles of pipeline. MPC’s fully integrated system provides operational flexibility to move crude oil, feedstocks and petroleum-related products efficiently through the company’s distribution network in the Midwest, Southeast and Gulf Coast regions. For additional information about the company, please visit our website at http://www.marathonpetroleum.com.

Investor Relations Contacts:

Pamela Beall (419) 429-5640

Beth Hunter (419) 421-2559

Media Contacts:

Angelia Graves (419) 421-2703

Robert Calmus (419) 421-3127

In addition to net income determined in accordance with GAAP, MPC has provided supplemental “net income adjusted for special items,” a non-GAAP financial measure that facilitates comparisons to earnings forecasts prepared by stock analysts and other third parties. Such forecasts generally exclude the effects of items that are considered non-recurring, are difficult to predict or to measure in advance or that are not directly related to MPC’s ongoing operations. A reconciliation between GAAP net income and “net income adjusted for special items” is provided in a table on page 1 of this release. “Net income adjusted for special items” should not be considered a substitute for net income as reported in accordance with GAAP. We believe certain investors use “net income adjusted for special items” to evaluate MPC’s financial performance between periods. Management also uses “net income adjusted for special items” to compare MPC’s performance to certain competitors.

This release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements relate to, among other things, MPC’s current expectations, estimates and projections concerning MPC business and operations. You can identify forward-looking statements by words such as “anticipate,” “believe,” “estimate,” “expect,” “forecast,” “project,” “could,” “may,” “should,” “would,” “will” or other similar expressions that convey the uncertainty of future events or outcomes. Such forward-looking statements are not guarantees of future performance and are subject to risks, uncertainties and other factors, some of which are beyond the company’s control and are difficult to predict. Factors that could cause actual results to differ materially from those in the forward-looking statements include: volatility in and/or degradation of market and industry conditions; the availability and pricing of crude oil and other feedstocks; slower growth in domestic and Canadian crude supply; completion of pipeline capacity to areas outside the U.S. Midwest; consumer demand for refined products; changes in governmental regulations; transportation logistics; the availability of materials and labor, delays in obtaining necessary third-party approvals, and other risks customary to construction projects; the reliability of processing units and other equipment; our ability to successfully implement growth opportunities; impacts from our repurchases of shares of MPC common stock under our stock repurchase authorization, including the timing and amounts of any common stock repurchases; the possibility the filing of the MPLX LP registration statement may not result in the pursuit or consummation of a public offering of units in a master limited partnership; other risk factors inherent to our industry; and the factors set forth under the heading “Risk Factors” in MPC’s Annual Report on Form 10-K for the year ended December 31, 2011 filed with the Securities and Exchange Commission (the “SEC”). In addition, the forward-looking statements included herein could be affected by general domestic and international economic and political conditions. Unpredictable or unknown factors not discussed here or in MPC’s Form 10-K could also have material adverse effects on forward-looking statements. Copies of MPC’s Form 10-K are available on the SEC website, at http://www.ir.marathonpetroleum.com or by contacting MPC’s Investor Relations Office.

A registration statement relating to MPLX LP securities has been filed with the SEC but has not yet become effective. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of securities of MPLX LP in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such state or jurisdiction.

Consolidated Statements of Income (Unaudited)

Supplemental Statistics (Unaudited)

Supplemental Statistics (Unaudited) (continued)

Segment Earnings Before Interest, Taxes, Depreciation & Amortization (Segment EBITDA) (Unaudited)

Select Financial Data (Unaudited)