The "Contains 10% ethanol" label means that ethanol has been blended into the petroleum gasoline—10% ethanol and 90% petroleum gasoline.
Have a diesel engine? You could purchase a biodiesel blend-fuel at one of many fueling stations. Its properties are similar to petroleum diesel, but like other biofuels, it comes from renewable resources and burns cleaner, emitting fewer pollutants. Look for the B20 label—although diesel engines don't need to be modified to use it, engines usually run better with a biodiesel blend, most commonly at 20%