My 2011 X5 35d sat for 16 days with the doors locked and alarm armed and it started right up first time. Zero hesitation or drama. I have not looked to see how old the battery is but I got my X5 in November. My driving routine consists of several one to two mile trips a several times a week and a 50 mile trip once every six or seven days. These longer trips are key, I think.

Incidentally, if you want the best battery maintainer, get a BatteryMINDer. I have several and keep them connected to my cars while they are not being operated regularly, i.e., greater than six months, over the winter, etc. I also use them on my spare batteries or other "bad" batteries that other people have given me over the years.

Between my recovery procedures and strict maintenance routine, I have recovered many of these "bad" batteries to greater than 95% reserve capacity. My oldest battery is over ten years old and recently tested over 120% of it's reserve capacity.

It's a hobby and a profession.

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8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim