I don't know who BMW uses as mfg for their battery now, but when the E53 left factory many moons ago, EXIDE was the supplier...
I really like EXIDE bc the quality is great and I can find it at Home Depot easily (search for availability first)...
The Walmart battery (Everstart ? sp) is made by Exide recently...
Here is a photo of the original BMW E53 battery, you can clearly see the word Exide on it...
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1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT
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