xenon headlights

Depends what you mean by Xenon, theres a lot of snake oil around these newer bulbs sold under various guises of Xenon, HID etc... A lot of what is sold as xenon are either xenon filled halogens or even just halogens with a blue glass tint.

Perhaps if you drop in a link to them someone can identify and help you further but based on the assumption that they are just glossed up halogens of one sort or another, lifetime will be the same as a normal halogen.

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1-4 000hrs, You can buy the bulbs on ebay way cheaper than the dealer. If the bulbs left in too long the ignition packs die as well.