I have repeatedly experienced short life from all types of Sylvania bulbs. My conclusion finally is that they probably used some of the engineers from their flashbulb division, to design their automotive headlights.
There is a different brand of headlight now available, which produces a brighter light than the Sylvania Ultra, has a wider beam; but does not cost more, and lasts much longer. It is the Wagner Brite Lite Xenon. These are not the same as the expensive HID Xenon lights; but they come closer to those lights in performance than anything else on the market.
I hope this helps!!!