Mazda is serious about its all-new engine technology, called SkyActiv. While US buyers of the also new Mazda6 will only have the gasoline SkyActiv 2.5-liter I4 at their disposal, other global markets will also have a new diesel option. And at this moment Mazda is seeking its 24th class win at the Rolex 24 at Daytona endurance race with a race-ready Mazda6 diesel. When prepped for Grand Am racing duties, this turbo 2.2-liter SkyActiv diesel with direct-injection produces an incredible 400 horsepower and 445 lb-ft of torque.