Batteries used to last 36 or 48 months, then they made it to 60 month warranties. They always failed very close to those dates, by design.

It is really hard to complain about any battery that goes eight years, particularly with all the ancillary draws that an X puts on a battery. You did well.

Ours is at 7 years in the X3, and it has just started exhibiting a very slight hesitation before turning over. It will probably go for months yet, but we will be in -30 C over the Christmas holidays, so I plan to pick one up next week.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue