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Thread: Reason for performance discrepancy of these HID lights?

  1. #1

    Default Reason for performance discrepancy of these HID lights?

    https://www.iihs.org/iihs/ratings/ve...a-4-door-sedan

    The lesser trims of the Giulia exhibit identical low beam performance on the straightaways. However, the lesser trims of the Giulia also exhibit significantly more glare than the higher trims of the Giulia (67%).

    How is it that the HID projectors in the lesser and higher trims have identical low beam performance but the lesser trims exhibit much more glare?

    I thought that in projectors, the cutoff is created by a piece of metal. How could this piece of metal have been changed to give identical low beam performance while letting more upward, stray light through?

    I want to say the results are the product of aiming discrepancies, i.e. maybe the lower trims use less powerful HID lamps and require more upward aim adjustment to actually hit the low-beam performance targets set by the IIHS, but the high-beam results don't support that theory.

    What's the deal here?

  2. #2
    *Flashaholic* StarHalo's Avatar
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    Default Re: Reason for performance discrepancy of these HID lights?

    Anyone who has the time and money to daily drive an Italian car probably won't get around to worrying about the headlights..

  3. #3

    Default Re: Reason for performance discrepancy of these HID lights?

    Look carefully at the specs: not the same headlamps. Curve-adaptive on the high trims only.

  4. #4

    Default Re: Reason for performance discrepancy of these HID lights?

    Quote Originally Posted by -Virgil- View Post
    Look carefully at the specs: not the same headlamps. Curve-adaptive on the high trims only.
    How would loss of the curve adaptive feature affect straightaway glare? I get that they're not the same, but their low beam performances are identical. It's just the level of glare that differs. Isn't glare just a function of the cutoff shield?

  5. #5

    Default Re: Reason for performance discrepancy of these HID lights?

    Quote Originally Posted by Ls400 View Post
    How would loss of the curve adaptive feature affect straightaway glare?
    Different headlamps, different performance characteristics.

    I get that they're not the same, but their low beam performances are identical.
    No, they aren't. Click the "Technical measurements" tab and see for yourself.

    Isn't glare just a function of the cutoff shield?
    No.

  6. #6
    Moderator Alaric Darconville's Avatar
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    Default Re: Reason for performance discrepancy of these HID lights?

    Quote Originally Posted by Ls400 View Post
    Isn't glare just a function of the cutoff shield?
    Forever and ever (amen): Cutoff is not the be-all, end-all for headlamp safety; the beam distribution under the cutoff can still result in excessive glare.

    Remember that, any time someone talks about a particular headlamp (or worse, their "retrofit" or "kit") and its "sharp cutoff". Cutoff is just part of the story and focusing on cutoff is to ignore so many other aspects of the light. For someone to home in on that demonstrates they have "learned" all they know about headlighting systems from the likes of TRS or some other vendor of light-shaped toys.

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