August 14, 2012. Tesoro Corp. agreed to buy BP Plc's California oil refinery and 800 gasoline stations in the Southwest for $1.18 billion, paying a below-average price for the facility as fuel costs soar in the region. Tesoro, the largest independent refiner on the U.S. West Coast, will pay about $1.3 billion more for crude and other inventories at the Carson plant. With the purchase, Tesoro will control 23 percent of California's refining capacity. The purchase will be Tesoro's third plant in California, a market with emissions regulations that are more complex than those in other states. The Carson plant is next to Tesoro's Wilmington refinery and the company projects it can save $250 million a year by combining the plants' operations. Excluding fuel, Tesoro said its cost for the refinery will be about $175 million after it sells associated pipelines and storage facilities to a master-limited partnership it controls. At that price, Tesoro would be paying about 15 percent of the refinery's replacement value, compared to an industry average of 25 to 30 percent. Tesoro said it's paying half of what Holly Corp. paid for a Tulsa refinery in 2009, on a per-barrel basis adjusted to reflect the plant's ability to convert crude to high-value products like gasoline. The geographic differences between the plants may have driven up the price of mid-continent refineries.