How do I determine what size 6 cylinder engine is in a 2009 Hyundai Santa fe

Has the hood been opened yet? Either large plastic engine cover will say it , or an emissions label under the hood. SOME places can actually determine the engine goung by the VIN#.

Try again... You just got a rookie/lazy parts person that time!... It does NOT matter which engine.... the batteries are the same for the 2.7 or the 3.3 V/6 engines!! Exact same part number!! You should look under hood like #1 said just so YOU know which engine is in your vehicle!!... Some times it DOES matter.