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I've got Xenon headlights and my car has a feature which automatically turns the headlights on at night. Currently I'm hesitant to use the auto-on feature because the headlights turn on when I start the car in the garage or park in the garage.

I know flicking on/off lightbulbs harm them in general, and I don't want to burn out the expensive bulbs. However HID bulbs don't have filaments if I read correctly, so I don't know if they'll burn out for the same reason.

The headlights come on unnecessarily about twice a day if I enable the auto-headlight feature. Will this significantly impact the life of the bulbs?

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I'm no expert, but I have the same setup in my car. I had to install a capacitor to give the HIDs constant power so they wouldn't get power at 60Hz. However, they do turn on and off once in a while, say going through a tunnel.

I haven't had a single issue with them in the last 2 years - since they were installed. As long as they have proper power when they're needed, I don't think it's a big deal.

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These are factory installed so I'm sure they're installed properly, just concerned about the longevity. The car's six years old but I'm not sure if the lights have been replaced. – Ben Brocka May 22 '12 at 18:29
They shouldn't ever need to be replaced - in the lifespan of the car. That is one of the key benefits of HIDs - they don't get that thermal shock wear that ordinary bulbs get. – Rory Alsop May 22 '12 at 20:47
@RoryAlsop Hm, really? So my 6 year old bulbs should last quite a while still for example? – Ben Brocka Jun 4 '12 at 20:38
Definitely! My garage was astonished I managed to kill one- turns out I caused it by damaging a casing that allowed water in, which then froze at minus twenty! £600 for a new one :( – Rory Alsop Jun 4 '12 at 20:47

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