2008 A6 4.2 Battery Replacement
 

Bigger engines = bigger batteries required - and the electronics package has to be programmed so the alternator doesn't over or under charge the battery and cause damage to both costing more down the road. The battery alone is $390 as best I can find online - my Euro Car mech is charging me $425 for battery + install = blew my mind I have never paid that much money for a fricken battery but I have a slight disability and my mech skills are long gone with all the new near air tight compartments on cars these days limiting access to only those with all the tools and know-how, AND it's time to change the oil at $130 a pop....so there goes $550+ out the window shoudla put it all on red!

Funny thing, when my battery started to really fade, it was taking a bit longer for the car to turnover / start, the driver door would not unlock by remote, and one day the stereo just took off and did it's own thing completely unable to control it by the buttons and knobs - scanning stations, stopping, and scanning, and not able to even turn it off, make a phone call and - anyways, my car was possessed by a poltergeist and replacing the battery was the cure - all back to normal!!

Sad part is, I just hit 75,500 miles and that means another $800 whopper for upkeep...draining and changing the transmission fluid and filter is $550!! And soon new struts to tighten up the S-Line -
I want to get out from under this but then monthly payments on a new sled - I don;t know - it's all the same just newer. Certified 2 y/o BMW 5 series may be in order....