FWIW.. My original battery lasted 9 months. I bought the car new in Dec of 2005, but I have no idea how long the car may have sat before it was delivered, as I purchased the car from an out of state dealer. I replaced it with an Optima Red Top, and, honestly, it was no better. Perhaps I got a bad one, but, in 1 year, it was toast. I replaced the Optima with a Bosch battery from Pep Boys, and it has served the car well for 3 1/2 years. The car can sit for 2+ weeks, and it will start the car perfectly.
I now use Bosch batteries in all my cars and trucks.