Of course it does, the battery is for the remote locks and arm/disarm - the start functionality gets power inductively from the ignition.

to change battery, remove the metal key blade and pop the rear cover off - it sort of slides off and you will find your batteries, plenty at your nearest pharmacy too.

I think its a pair of CR2025.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)