How much gas does a hyundai sonata hold?

The Hyundai Sonata has an 18.5 gallon gas tank in the vehicle. You should use a regular unleaded gasoline with an octane rating of 87 or higher. Do not ever put E85 or diesel fuel into Your vehicle because it can destroy Your fuel system and engine. I recommend always using the highest octane fuel that You can afFord. A higher octane fuel will burn more completely in Your engine and that can reduce the carbon buildup in Your engine. There are also gas options on the market that are labeled as top tier. These have additives and detergents in them that can break down sludge in Your engine to help it last longer and prevent wear and tear.