I've been wondering the same since last winter...I've been carrying some thick jumper-cables since ~Oct '13. My battery finally died this a.m. I drove ~280 miles yesterday without issue. This morning...dead. Would not even think of turning over. The only hint it was coming was a slight hesitation starting last night after trip. OEM battery was clean. No corrosion. Plenty of electrolyte. Looks "new".
I replaced with an AutoZone Duralast Platinum. After reading about it, I now wonder/wish I got the flooded "Gold" rather than the "AGM" "Platinum"....but...at least it was fast and easy. Discovered the dead battery at 8:15 and made it to a 9:30 meeting with time to spare, so not an ordeal at all.
Only funny *stupic me* story from the break down...when the AutoZone Tech pulled the battery, I noticed there was about a teaspoon of water on the tray. I thought I'd wipe it up since the water would be trapped under the new battery. Went into the store to get a paper towel. Came out, wiped it up, and walked to throw away the towel. Not wearing gloves, and the towel soaked through, I thought...hmmm...I wonder if that was water or acid. My hand was already wiped dry. I'm a chemist and know what H2SO4 can do, so I went to the john to rinse my hand. On the way, to check if it was acid, I touched my (formerly wet, but now dry) finger to my tounge. Sour-Ouch. f'kin acid. I spit and rinsed my hand clean. Rinsed my mouth. Tounge still burns and I have bad taste in my mouth. Colleague says dryly..."Yeah...bad idea tasting stuff from your car."
So...for me...OEM battery lasted 4 years 10 months. Never drained the battery, and I am only driver. I had two "intercooler icing" events where I needed to draw hard on the battery to get car started. Also, I use the key-in-door to roll down all 4 windows before getting in car when it's hot...that is the only drain I put on the battery prior to starting. Other than that, it's 12 mile commutes and gentle treatment. I added water to the "maintainance free" OEM battery twice.
'nother thing...after battery swap...my settings were wonky. Stuff like the window auto-roll up/down did not work right. After setting them correctly and rebooting the car, it all seems sorted out. Some settings did not kick in until the second restart. Dunno why.
Cheers,
Joe