i would suggest use dealership to replace battery if you want to avoid headache for saving few bucks, it is not easy to do if u are not do it yourself kind of guy.

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2013 X3 XDrive28i Sapphire Black Premium Package, Technology Pack, CWP, SAT Radio, BMP APPS.
2013 328xi Mineral Gray, Moonroof, CWP
E90 2011
E90 2007
E46 2005