What type of fuel does the 2013 ford focus st take?

The 2013 Ford Focus uses regular unleaded gasoline with an octane rating of 87 or higher. You should never use E85 of diesel fuel in Your car because it can damage the fuel system or the engine. I recommend that You use the highest octane rating that You can afFord. A higher octane rating will burn cleaner and more completely in Your engine and that prevents carbon buildup on Your pistons and valves. There are also fuels on the market that are labeled top tier. These have detergents in them that are designed to clean sludge out of Your engine to keep it running well for longer.